Android vs. Iphone vs. Blackberry

I need a phone or tablet pc and i have done my research but I am still undecided.

My telephone company is t-mobile and i would like to get a data plan.

I heard virgin mobile has a unlimited data plan for $60, would this be a good idea?

I need to talk to someone who lives in Asia. Which phone would you think is the best bang for the buck and relatively cheap?

Thank you