I had a 3G iphone.... it was slow as hell, plus the fact that at&t seems to no longer have 3g anywhere, let alone 4g.
I tried using my uncle's 4G for a while, but I was still convinced that it sucked. When I loaded up the memory on it, it slowed down drastically.
Now, I have a Droid X, I am quite simply amazed that anybody would EVER get an iphone.
It has about a quarter gig of free space and is running as smooth as if it had nothing on it what so ever.
Droids are also more customizable, which is a plus.
And lucky me, I got myself an unlimited data plan with Verizon just before they stopped giving unlimited plans.