Brazilian Mobile (São Paulo)

Hello I am an European moving to Sao Paulo from USA. Over here I always used an iPhone and I was planning to get one in Brazil as well but some friends suggested me to go for a BlackBerry instead since, according to them, is much more popular in this country. Do you have any suggestions?
It would be also extremely helpful if you could suggest me which phone company to choose, considering that I will definitely go for a contract (not pre paid card) and I am an heavy mobile internet user.

Thanks!!!