I myself use 俺は （Ore wa） with my friends. Its kind of rude (to other people) but sounds cool.
Boku wa （僕は） is actually; more or less; polite, and as stated by SamuraiAlchemist-san, is used by males, generally 3-20 years old but not limited to 20. There is an exception to which some Japanese girls (tomboys) who say this as well.
I don't know why, but there are two posts that are the same. 