Well, at my site we had this match in the tournament thread (you can look their if you want, kamikz, you still got the link? It's the first page of the tournament thread, but I won't post the link here for anyone to go to). Quinlan won with a 3-2 vote, and I was one of the ones who voted for Quinlan. It's be very, very close, though. Here is some of the stuff that I said and other people said on my site:
Quinlan's younger, stronger, in better shape (though Qui-Gon's not in bad shape) and he has kileld more than one Dark Side Acolyte.
Has killed Volfe Karkko, Sora Bulq, wtf pwnd Tol Skorr, was able to summon Force Lightning with no training in that category, and kicked tons of ass in EU.
Vos survived Order 66, successfully convinced Dooku that he turned to the Dark Side when he really didn't and, after truly turning to the Dark Side, convinced the Jedi Council Members that he was really on the good side still.
I would say in a saber duel they would perhaps be equal except Qui-Gon is more likely to tire out faster, giving Quinlan a slight edge in a saber fight. However, Qui-Gon was strong enough in the Force that he taught hismelf to return from the dead, and so I would put Qui-Gon's Force Skills above Quinlan's, but will Qui-Gon use them in a fight? He didn't when he fought Maul.
Quinlan also beat Tol Skor and Kadrien Say at the same time, Jinn could maybe do that but not as easily as Vos did. Plus ROTS Vos is even a little bit stronger than he was when he beat them.
Vos has bigger biceps than Jinn does, too.