I want Floyd to win.
The first thing I'd judge a fighter by is their actions in the ring. And in that regard, Floyd's my favorite fighter out there.

In the short term, I think it'd be good for the sport if Oscar wins.
But the thing is, Oscar's already a star out there. He could beat Floyd, he could beat a plumber, he's always gonna be a star. He's always gonna be a major draw.
When If Floyd wins, he's gonna get major attention for the win and increase his drawing power. And in the long term, I think it's a lot better for the sport to have big star attractions.
Win or lose, Oscar is cemented. But Floyd could easily fall into a heavy decline with a loss if he handles it poorly.

If Oscar loses and comes back to fight again, people will still come in droves to watch it.
I don't know if I can say the same for Floyd since so many people tune in to a Floyd fight to see him get his block knocked off. And if it happens, the luster of his invincible persona is tarnished.