Uhh thats kinda hard to answer cause nobodys gonna be happy with it. Nu metal is a kind of contraversial genre because nobody agrees on what it is exactly and every artist seems to say that theyre not actually nu metal. My top five would be Korn, deftones, limp bizkit, slipknot, system of a down. The most famous is probably linkin park which you definitely know but they are kinda their own seperate entity. Rage against the machine is also kinda seperate tho still kinda nu metal. As for songs i recommend to get s feeling for the genre: Freak on a leash, blind, break stuff, change, be quiet and drive, aerials and eyeless.