I've had every iPhone released. The 3GS IS Apples finest by far.
In fact over a three month period, I bought six of them from Apple, one for each member of the family.
Presently my wife and I have each had more than one iPhone 4 due to a host of problems. None of which are the antenna or AT&T.
I truly believe Apple took shortcuts to rush it to market ahead of the release of all the Moto Droids on Verizon.
As a result there's always something wrong. What a pain in the ass the iP4 is.
So we went back to the 3GS for her.
I'm still living with my flaky 4, but have Android phones to use as primary devices.
My current favorite Android is my AT&T Inspire. It's the best of my Androids with the Droid X being second.
Good luck, with an iPhone you're going to need it.