I would go with the Blackberry Pearl.
I own it and love it!
It's sized like a phone. (You may get other blackberry with full keyboard but it's bigger)
The Blackberry pearl comes in five colors and it rocks!!! it comes with 1.3 megapixels camera and with several features.
It has full internet and e-mail capabilities and you may even use it as a modem (You will be able to connect any computer to the internet just plugging the phone -after proper installation- from anywhere you have T-mobile signal)
This phone has a reliable battery, bluetooth, full color screen and several features more.
T-Mobile has a dedicated blackberry department where employees are friendly and helpful!
It's price is very reasonable. If you get two years contract or you are eligible for an upgrade, you pay $100 and you get $50 of mail in rebate.
I really recommend you this phone. I need to connect both my phone and my laptop from my car and it never failed me.