OOOOOH this thread is WAY overdue!!!
DBZ has been my lifelong favourite-ESTTTTT show ever, EVERRRR. Best thing to happen to TV!
My fav baddie was Freiza - much more evil than Cell and unlike Cell who had to be 'artificially constructed', Freiza was more 'real' in that sense, which somehow makes him more frightening and evil. Also he was just more evil anyway with all the stuff he did for no reason whatsoever - Cell was programmed to destroy by Dr Gero so we cant really blame him a whole lot.
Favourite fight...really cant decide..DBZ had some totally amazing battles. A few of the most epic ones for me were the first fight between Goku and Vegeta, Piccolo vs Android 17 (seriously underrated!), Goku vs Freiza (of course!) and the Z-fighters vs Androids/Cell - especially Gohan's incredible transformation - epic on another level!
Best Saga would probably have to be the Namek Saga..I love everything about it, the voices of the characters, Namekians, story, events, EVERYTHING was PERFECT. But really I love the whole thing..wow they really need to bring that kind of TV back - I would still watch it with as much enthusiasm as I did all those years ago!