Its all depends on what you want, if you want a keyboard to go with your phone, get the google g1. On t-mobiles site it costs 399 to buy, the same with the my touch.
Over all with features included, I would pick the Samsung Behold 2, its the phone I ended up buying and I dont have a contract. Though i decided to buy it brand new on ebay and i got my for 290. If you want it new on t-mobiles site it is 499. But they can split your payment so you only have to pay 15 dollars a month for it for 20 months with no interest.
The Samsung Behold has an amazing battery life, and an amazing screen with amold, it has a 5 megapixel camera and is great to watch movies on its screen and listen to music. And it has wifi real web surfing. So even if you dont get a data plan, you can still get on the internet when wifi is around.