Well I've had the iphone 3gs and currently the Optimus T. With that said the Optimus T is an excellent device. The screen is a little smaller but were talking .3 smaller. In return I get great battery life. The device is snappy enough for me and overall is a real sleeper. Brand New I paid $100.
If I could suggest any other phone it would be the Motorola Defy which has a bigger screen and has gotten some great reviews.