Fox, Sheik, and Roy ... in that order of preference ... Fox and Sheik, because of their insane speed (because in my most honest opinion, speed is a hugely essential factor in especially one-on-one brawls -- and Sheik is probably the only character with whom I can make actual use of the side-step dodge, haha), and Roy, because of his awesome counter move. My favorite level is undoubtedly Final Destination, primarily because it provides the fairest match possible between opponents (no environmental hazards or anything of the sort.) Hyrule Temple is a close second, because of its massive-ness. :D