I hate to be the sports elitist here. But it should be MMA, not UFC (Unless you specifically meant UFC all in itself....which is unfair since most of the lower class MMA fight cards are really entertaining since the guys are just fighting for whatever money and reputation they can earn) I would go with MMA though slightly. I hate the judging system for UFC in particular (3 rounds so high variance). I know some other MMA promotions to based off of total fight performance.
I liked boxing better when Mike Tyson was in the sport, loved to watch him fight. I prefer the UFC these days, its more entertaining to watch.
It's MMA. Mixed Martial Arts. Not UFC. UFC is one organization - obviously the biggest. The sport isn't called UFC though. Like I said, it's MMA. Nobody refers to boxing as WBO. They call it boxing. There you go. Now you're more educated!
UFC is a great sport but if I had to choose one I would have to go with boxing. The classic last man standing sport.