Vegeta would've ended the series early, he was too above them to win without everyone's input. I don't even think Gohan going Oozaru would've helped much, since Vegeta could actually control the form and not be a walking raging monster. With a level playing field, my money's on the one with intellect and battle experience on his size over raw power (and I'm not even sure if Oozaru Gohan is stronger than Oozaru Vegeta).
