Smart Phone

I never bought a smart phone before, what type of phone should I get?

My profile:
Designer/Developer
Works with designs(web, UI, game design)
Most communication by email.
I rarely call people, but I do need a good connection as I call people a lot at or near my job and around the subways.

I would like to use apps but for business and development, not for fun.

t-mobile carrier

Age:
25+

My computer:

15in. Apple MACBook Pro

Thanks