For your brother I recommend Twilight princess as it has a fairly low difficulty and the least annoying. OOT is a challenge and he may get stressed and give up and we don't want that at all however it is a great experience and has great atmosphere.It also will provide him with the best introduction to series villain Ganondorf and the begining of the zelda timeline(excluding SS as it is not yet released) If you were to help him though any part he was stuck on he may enjoy the experience more. WW has a very very very irritating tingle quest and the wind temple is also stressful so I would not reccomend that as a first game.