That was last year. I have to go with Ortiz/Lopez. There was tons of back and forth action in that fight.
I disagree with the assumption that a fight that is less than six rounds can't be FOTY. Foreman-Lyle, anyone? I do agree that one sided fights shouldn't be up for consideration, though. Salido-Lopez, Alvarez-Herrera, Brook-Jones, and Ioka-Yaegashi are all front runners, and do meet all of your criteria, it should be noted. But if a five round fight is crazy enough to over-take it, then so be it.
taking everything into account its got to be haye-chisora...everything about it was brilliant...the munich brawl, the fight buildup, the weigh in, the atmosphere at the fight was the best ive experienced and the fight itself was the most exciting all action heavyweight fight theres been for donkeys years. i dont know about the rest of the world but it got so much press in the UK...it really helped get the neutrals interested in boxing again. and the icing on the cake...haye becoming the first man to put chisora on his backside :-D
Salido vs Juanma 2 by far the best But Matthysse vs Soto was one of my favorites this year, far better than Ortiz vs Josesito Lopez or Khan vs Garcia