I came from a 2G/3G/3GS iPhone that was unlocked and jailbroken for the T-Mobile network. Loved it. Customizable, never ending apps, and most important, free paid apps. Only down fall was not being able to run 3G services due to the difference in towers between AT&T and T-Mobile. I grew old of it so i decided to pull the trigger. I sold my iPhone and made a switch to the darkside, Android. After owning a Galaxy S, Google Nexus One, and my soon to be Google Nexus S that is on pre-order, Android just seems more fulfilling to me. I love both phones, don't get me wrong, but I find the Android OS superior to the iOS. Having an iPhone is great, but people only seem to care for it as a "status" symbol if anything. Android is on it's way. Mark my words.
ANDROID ANDROID ANDROID
If you want to get the best out of your hardware. And if you don't want to have the same phone everyone else has. I've had windows (ehhh), BB (pretty good for work), Iphone (you can only download so many fart apps), and then Android. I'm the kind of person who always changes my phone every few months. But I've been on the Droid Incredible (it is incredible) for awhile now. And the best thing about Android is flashing new roms. I do it every 2 weeks and it's like a new different phone every time.