Fighters of today's era that could fight 15 rounds?

No mention of Vazquez yet!

 

Sugar Shane.

 

From an athletic point of view probably every fighter would be able to go the 15. If you are asking which fighters would be better over 15 rounds then that is a different question which I'll answer (whether you were asking it or not).

I think defensive fighters that naturally come on strong in the 'championship rounds' would be be better over 15 than 12. For example B-Hop, Winky and Floyd. I think there is a notable exception in Joe Calzaghe as someone who could do what he does now over 15 rounds without having to change his game too much.

Than you've got the lighter fighters with low KO ratios, like Calderon who someone mentioned earlier. But these fighters would probably cancel each other out