don't choose a school - choose a teacher, that's most important. if you have chosen the right teacher, you'll learn everything you need to know from him/her - not just piano, but also theory, harmony, counterpoint, stylistics, aesthetics, and so on.
how to choose a teacher? preferably you should "shop" while going to concerts - if you say you wish to become a pianist (as opposed to a person playing the piano), you will need to work with a pianist rather than teacher; then go talk to this pianist. you will probably figure out for yourself who's the best teacher for you.