The best boxing commentator I have ever heard was Jim Healy. He used to do the fights from the Olympic Auditorium when I was a kid. (They would play, live on the radio, I think, then a week later on television). He didn't talk too much and he generally limited himself to pertinent and fight related comments, as opposed to these buffoons that think the fight is only interesting if they are talking too.
The best part is how, when the crowd would go wild over a punch, he would tell you, from ringside, if it had actually landed and if it was effective. and he wasn't biased and one-sided in his call of fights.