I have owned all but the iPhone 4 and 4S now. After the 3Gs I went to a Galaxy S, SO much better. I cannot even put into words how much better Android is, to me, over iOS.
I recently waited to October 4th to get a new phone, to give Apple a fair chance at getting my money. And they failed hard, as usual, and I now have a Galaxy S II. Which, from what I can tell will crush the iPhone 4s into the ground.
Galaxy S II has a Dual Core 1.2Ghz CPU while the iPhone a 1Ghz Dual Core.
512mb of Ram on the iPhone 4s, while the Galaxy S II has a full gig of RAM.
3.5" screen on the iPhone 4s as compared to the 4.3" on the Galaxy S II.