It may sound like a basic question but I'd be fascinated to read people opinions. Personally my Favourite is either Pippin or Gimli. Pippin because to me hes almost the embodiment of innocence at the beginning, just wants to have fun, and loyal to his friends, like to joke and laugh and has no real malice at all. He keeps that innocence as well especially in how he is depicted in the movies. Especially when he volunteers to join the fellowship, He doesn't really think about it he just kind of goes my friends need me and nothing will stop him helping them., same with serving Denathor again he doesn't really think but knows he is doing the right thing. The Tooks are a family I am really interested in.
I like Gimli because he is nothing ever than himself, he isn't coy about sharing his feelings or opinions and if you like him and treat him well hes loyal till the end. If you are rude he takes no shit (this might just be a Dwarven trait to be fair). But what makes him one of my favourites is the gift he got from Galadriel. It shows his true heart and what he treasures is beauty and not necessarily power. Also by how he is willing to fight for his beliefs even challenging Eomer for not saying Galadriel is the fairest. So that's my humble opinion what is yours?