I will break this down in 2 places; hardware and software. I will BRIEFLY dive into the difference in the networks but only to shed light on a specific point. I will also make references to older model iPhones but the basis of this is comparing the iPhone 3GS and to the Incredible and I will speculate on how the iPhone 4 stacks up. Those are the terms of this comparison.
These phones pack some very serious System on a Chip (SoC) hardware. The specs break down as followed:
Processor - dual core 1 GHz Qualcomm QSD8650 Snapdragon @ 768 MHz
RAM - 512 MB
GPU - No dedicated GPU
Battery - 1300 mAh (stock) current available upgrades to 2100 mAh
Storage Capacity - 8 GB internal storage, up to 32 GB removable micro-SD
Wireless - Wifi B/G, dual band CDMA network upload @ 3.1 Mbps, Bluetooth 2.1 + FTP/OPP, FM radio tuner
Screen - AMOLED 3.7 inch multitouch capacitive touch screen @ 480x800 with Gorilla Glass
Input - multitouch capacitive touch screen, optical trackpad with click to select, 4 dedicated soft keys, side rocker buttons and standby button.
Camera - rear facing 8 MP with LED flash
GPS - assisted and non assisted GPS
Processor - single core ARM Cortex A8 @ 600 MHz
RAM - 256 MB
GPU - PowerVR SGX530 @ 200 MHz
Battery - 1200 mAh
Storage Capacity - up to 32 GB internal storage (now limited to 8 GB)
Wireless - Wifi B/G, multi-band GSM/HSDPA download @ 7.2 Mbps, Bluetooth 2.1 + EDR
Screen - 3.5 inch multitouch capacitive touch screen @ 320x480 with Gorilla Glass
Input - multitouch capacitive touch screen, side rocker buttons, accelerometer, home button and standby button
Camera - rear facing 2 MP no flash
GPS - assisted GPS
Processor - single core 1 Ghz Apple A4 (ARM Cortex A8)
RAM - 512 MB
GPU - PowerVR SGX545 @ 200 MHz
Battery - 1420 mAh
Storage Capacity - up to 32 GB internal storage
Wireless - Wifi B/G/N (2.4 GHz only), multi-band GSM/HSDPA network download @ 7.2, Bluetooth 2.1 + EDR
Screen - 3.5 inch multitouch capacitive touch screen @ 640x960 with Gorilla Glass
Input - multitouch capacitive touch screen, side rocker buttons, gyroscope, home button and standby button
Camera - rear facing 5 MP with LED flash and forward facing VGA camera
GPS - assisted GPS
These phones have hardware that is state of the art. You can see how the iPhone 3GS lacks the Incredible's CPU brute force but it makes up for it with the dedicated GPU. This really shows with video playback and gaming on the Snapdragon hardware blows the iPhone 3GS out of the water. Playing the cross platform game Cestos shows that the 3GS doesn't render as fast as the Incredible but still plays smoothly. The iPhone 4 steps up with similar hardware to the Incredible but the Incredible still pulls in the specs game. Even though the Incredible in underclocked to 768 it is possible to root the phone and overclock it to 1.1 GHz which would obliterate the iPhones. Sadly I don't have any standardized way of benchmarking the hardware but my computer tech experience tells me the Incredible wins this one.
GPS is a side point though important to me. I'm not entirely sure that the 3GS uses the GPS satellites but just uses the cell towers to coordinate. However, the GPS in the Incredible actually uses the GPS satellites but can use the towers to coordinate as well. No one gets a point for this though.
The battery is a key point. The 3GS has a good battery life for a smart phone but leaves huge room for improvement. You also have to break into the case to access the battery. Changing out the iPhone battery isn't something the normal day to day user will do. The Incredible though actually loses and then wins in the fight in this comparison. The battery life seems to be better for me on the iPhone compared to the Incredible. However, HTC made the Incredible so you can remove and replace the battery easily by simply unsnapping the rear panel. I have an upgraded battery @ 2100 mAh for the Incredible coming in increasing the battery from the stock battery @ 1300 mAh. That is a HUGE upgrade and should beat the 3GS AND the iPhone 4 in battery life. Another point here is that Apple seriously upgraded their hardware to compete but the battery power seems to be a minimal improvement. We'll see how it stacks up after the launch but another point for the Incredible.
Cameras on a phone are a big feature these days and have a ton of usefulness in them. The iPhone 4 made a small improvement in camera capacity going from a 2 MP camera in the 3GS to a 5 MP unit but it still lacks compared to an 8 MP module in the Incredible. The iPhone 4 does pack a front facing camera for those oh so important facebook profile pics so unless your a 14 year old girl hell bent on changing your profile pic every 15 minutes or you do a bunch of video calls your main concern is probably gonna be with the rear camera. I say the iPhone 4 and Incredible tie in the camera department just because the iPhone 4 has a second camera.
For the wireless department the iPhones win. While the original iPhone was EDGE only the 3G, 3GS and iPhone 4 run the 3G network. The 3G doesn't pack the theoretical 7.2 Mbps hardware the 3GS and iPhone 4 has but its better than 2G. Both the 3GS and 4 have faster theoretical transfer speeds than the Incredible giving both the 3GS and 4 a point. However, the 4 has something the 3GS doesn't have which is the Wifi N band.
The phones all pack digital compasses, Bluetooth 2.1 and good buttons; they tie in those fields.
The next place the Incredible wins is the storage arena. With 8GB of internal storage it places it on par with the new iPhone 3GS (Apple changed the capacity down to 8GB ONLY but the 3GS used to have up to 32 GB) . My 3GS has 16GB but loses because I can add 32GB to the Incredible's 8GB for a total storage of 40GB. The Incredible gets a point.
The screen battle is a dead tie between the iPhone 4 and Incredible. The Incredible has a taller screen but the iPhones' screens are wider. The iPhone 4 has a slightly higher resolution than the Incredible but the Incredible has an AMOLED display. They all have multitouch capacitive touch screens but the iPhones definitely have Gorilla Glass. I'm getting mixed reports that the Incredible has and doesn't have Gorilla Glass so no one gets points until I find out. I feel MUCH better having the Gorilla Glass on my iPhone though. Note: I spoke with HTC's technical support; they confirmed that the Incredible does have Gorilla Glass. Dead tie.
The iPhone 4 gets a point in the accelerometer field for it's use of a gyroscope instead of an accelerometer/G-sensor but that's a side point.
From where I'm standing the Incredible is winning the numbers game but hardware is definitive. How you use that hardware is what matters and you need software to properly use that hardware. Lets check out the software side.
iPhone 3GS - 1
iPhone 4 - 3
Incredible - 4
The mobile OS field is a very important field right now. 2 new contenders, Apple's iOS and Google's Android are sweeping the game and tearing down old players like Palm who actually recently got bought out by HP. Microsoft is desperately trying to update their aging Windows Mobile platform with Windows Phone 7 while it's ratings continue to plummet. RIM's BlackBerry OS is still one of the most prominent mobile OSes out but is seeing it's number drop as well and Nokia still sells a ton of phones.
But how do the new kids on the block do when they duke it out with each other? Well, its all about personal preference which is why I won't be scoring them by points or at all for that matter.
iPhone 3GS and iPhone 4
OS - iOS 4.0
OS - Google Android 2.1
When Apple launches a new version of it's iPhone it launches a new version of it's iOS. They did it with iOS 3.0 and the iPhone 3G and 3GS. They did it again with iOS 4.0 and the iPhone 4. iOS 4.0 is very VERY major update for the platform because it opens up a few features that really help the OS back. Specifically, multitasking and, for me, wallpapers.
My biggest beef with iOS is that I can't do a lot of customization. In the stock configuration I'm limited to a hand full of silly and lame ass ringtones and sound effects for new text messages. I can't even change the sounds for new voice messages and email (at least those are different between the 2 events). My Motorola Q9m with Windows Mobile 6.0 let me have the Final Fantasy chocobo theme song for my ringtone, a zombie scream from Half Life 2 for text messages and any noise I wanted for email and voice messages. I could choose the layout, the background and even the style. That phone was great and wasn't half the phone these are but that's why software is important.
The problem seems that Steve Jobs thinks he knows EXACTLY what I want. He's close but he needs to let me play with the toys that I "purchase" with my money without having to root/jailbreak the device. Thankfully, iOS 4.0 lets you do something you weren't allowed to do which was use a background image or wallpaper. Initially their idea of wallpaper was an image that you briefly saw when you hit the standby button to unlock the phone but now you can see your favorite pic when navigating through the pages of apps too.
That silly thing aside, iOS is a fantastic OS. It's a great environment with minimal security holes. iOS 4.0 makes the system a little better with multitasking. Opponents to iOS always say there isn't any multitasking. That is BLATANTLY false. Email/text messaging transfers, calls, clock, events/calendar, alerts, music and wireless networking all run in the background. Before 4.0 you couldn't run a calculator then switch to notes with out losing something unless the app was set to remember what it had last. No you couldn't start loading porn in Safari and play a game while you waited but multitasking was there. Now iOS has a very limited form of multitasking which is that if you are using an app you double click the home button and an app menu opens open. The menu only shows the apps that have multitasking support. That means that if you are playing Plants vs Zombies then you can switch to Cestos then switch to Safari then switch back to Cestos and switch to Plants VS Zombies without either game being reset. That is really nice because on more than one occasion I have lost games because someone called me while playing PvZ and I accidentally hit the home button after the call.
Multitasking really helps the iPhone out. iOS also adds features like animations and changes the transition rates between pages. It also adds email threading which is really nice but it changes the accounts layout too. Personally I liked it the way it was but if they had just added threading instead of everything they added (or at least let us be able to change the layout ourselves) it would have been awesome.
Otherwise, iOS's biggest strong point is that it has a very minimalistic approach. There aren't lots of menus and sub-menus. You aren't bombarded with options and things to click on that will get you lost easy. That's why I really love the iPhone. I'm already ADD, I don't need my phone perpetuate the cycle. That reason alone is why many people just have regular cell phones. My grandmother has an old Trac-Phone for emergencies that is really easy to use and easy to use is exactly what has allowed Apple to sell so many iPhones.
The downside to iOS and subsequently Apple is the lack of love for technical people who like to play with and change their devices. I don't know if Apple doesn't want you to customize or they just don't want to put anything in there you can change but I would like to be able to change things when I feel like it. Most of the time I'd rather leave my phone alone so that it works when I need it but sometimes I really like to be able to tweek and mod my phone to do cool stuff.
Which is why I also like Android. If I root my phone, Steve Jobs won't yell at me and ban me from iTunes because I wanted to change my sound effects. Also I like Android its linux and because it's free and free is awesome.
Android is easy to use and customize visually but I still wish I could change the sounds for messages. Android also does a few little things like enable/disable wifi without dropping a call which is cool. But the email layout needs to be laid out better. I really think copying Apple on the email layout would be okay.
You can't talk about iOS and Android without talking about apps. Guess what? iOS has apps. Guess what else? Android does too. Android has an app store and so does iOS. Yes iOS has 100,000+ apps. Do you have ALL OF THEM? I sure as hell don't. Android's Market has 30,000+ apps and that is nothing to scoff at. iOS fanbois get ready because Android has more than just apps; it has WIDGETS! Widgets are freaking great because instead of hunting through settings and pages of apps I can have widget that tells me exactly what I want. Like real-time weather updates and have the ability to change the brightness from the home screen. I can disable wifi or bluetooth by pressing a soft key. I can call my work or my girlfriend with a quick double tap. Widgets are great for quick information or changes. It definitely puts one to iOS.
Update (Feb. 2014)
In the end while I liked the Droid Incredible, after about 6 months of usage I had some VERY annoying issues with the touch screen not registering. Eventually I replaced it with a $99 iPhone 4 on Verizon in October 2011. As of this update, the iPhone 4 8GB is still running good and looks near brand new due to Otterbox cases. I did upgrade to iOS 7.0.4 from iOS 6 after a very long wait resisting the upgrade but after doing the upgrade I'm highly disappointed with iOS. The new look and the severe sluggishness are becoming a serious annoyance. Because of those issues, I am considering upgrading to the iPhone 4S 8GB as Verizon has them at $0.99 with new contract just so I can get the slightly better processor to deal with the iOS update issues.