Just to respond to a few of the names mentioned:

Tyson- had a devestating left hook, but when I think of Tyson, I think of straight right hands and uppercuts, those were his true money punches and the punches he scored most of his KO's on

Lewis- definitely doesn't belong on the list. his entire attack was based on the left jab and right cross. The left hook was an afterthought to Lewis.

Mayweather- the left hook has been a big punch for him, but he has nowhere near the power in his left hook that Trinidad had in his prime. Mayweather is a great fighter because of his defense, not his punching. Could you imagine if a prime Tito at 147 landed a flush left hook on Ricky Hatton?

Micky Ward- ya he had a good left hook to the body, but the fighters he was landing left hooks on weren't even remotely the same caliber as TIto's opponents.

De La Hoya- I figured his name would come up, and he definitely has a great left hook. But I don't think his hook had the power of Tito's. Look at their fights with Vargas. Oscar knocked out Vargas with a hook, but not until after he had picked him apart and worked his body for 10 rounds. Tito badly hurt Vargas with the first left hook he landed, only 20 seconds into the fight.