I'm going to go with Zell on this one. While Snow has the better character design, he lost out on personailty with his constant: I'M THE HERO! SERAH WANTS US TO SAVE COCOON, SAVING COCOON IS OUR FOCUS, I'M SERAH'S HERO WHO MUST SAVE COCOON CAUSE THAT'S MY FOCUS AND THAT'S WHAT SERAH WANTED!!!! For 20 of the forty longest hours of my life.

Zell still had some great comic relief moments, his banter with Seifer was amusing, and his sidequest with the librarian was pretty cool even if it was poorly executed. Also, he can do this: