It's all about horses for courses. I will always prefer boxing, but some MMA stuff is great to watch. I was watching some MMA the other night (don't ask me who was fighting) and it was a brilliant, action-packed fight. I thought to myself, "Hey this is really, really good!" If there were more fights like that, I'd make a point of watching it. I enjoy watching any combat sport though - kickboxing, K-1, MMA, greco-roman, sumo and of course boxing. If it's good, it's good.
Much, much prefer boxing. Will watch MMA if there's nothing else on the TV, but I will plan an entire weekend around a good boxing matchup. In fact, I planned my last holiday around the PBF-Hatton fight. Booked the flight for the day after, stayed up all night playing poker, took a break for the fight (live in Ireland) and then finished poker, had a shower & went to meet my gf at the airport. MMA leaves me cold to be honest.