Bought the OG Droid on release day. Have a lot of experience with rooting it, tweaking it, loading various custom ROM's and overclock kernals, etc. Was always disappointed by how it ran in comparison.
Kept it for just over a year and then switched to the iPhone 4 and was blown away by how much better it ran. The OS, quality of apps, battery life, etc.
Recently my wifes phone broke so I gave her my iPhone 4 and picked up a DROID RAZR and took it back after 9-10 days of use. LTE was nice, but destroys your battery, and battery compared to my iPhone 4 was subpar under mid-heavy utilization.
My 4S is on the way... well it's ordered anyways.
So yes. I've used one extensively of both original and current generation, and have kept going back to iOS.
I don't see going back to Android for at least another year or two. ICE is definitely on the right track, but not one of the phones (including the Galaxy Nexus) matches the overall iPhone quality completely. I don't know why, but every Android camera I've seen just doesn't match up and that's a big thing for me with 2 kids.
LTE is very nice, but the tech is too new and it destroys your battery. Since I'm a mid/heavy data user lately since I work the night shift it's just too big of a deal. Hopefully in a year or so the new LTE chips + new phones will be able to find that middleground to make LTE the "norm" for business users (I also use my phone for work).