Very first was the Palm Treo 700p on Verizon. Then got the iPhone 3g on AT&T, then iPhone 4, then sold that to get the 4S.
I tried out my friend's Droid 1 for like 10 minutes (this was in the days of Android 2.1), and it was a little complicated. The back button which is different from home button, depending on the application? Im sure I could figure it out eventually, but iOS was simple for me.
I just got a HP WebOS Touchpad; I love it. It is a solid OS and it was a good decision for HP to Open Source it. Of course it would have been better to continue producing devices, but whatever. Honestly, if there was a solid WebOS competitor to the iPhone for my next phone, I wouldn't know which one I would buy. Probably iPhone because I already bought all these apps, but it would still be tough.