There are so many aspects of the word 'favourite':

Zidane wins Best attitude award
Garnet wins, uh... Thinnest character award
Eiko wins Most energetic character award
Freya wins Best character in battle
Amarant wins Coolest character award
Steiner wins Funniest character award (along with Quina)
Queen Brahne wins Most vulgar character award
Vivi wins Most innocent character award
Quina wins Funniest character award (along with Steiner)
Beatrix wins Best character evolvement award
Kuja wins Best boss award