I can't think of any that top Castro vs Jackson, as it was so one sided until what was truly a desperation one punch KO. Even Foreman against Moorer, if you watch carefully Foreman was setting him up for a while and getting closer and closer when he did throw the right hand. Leonard hurt Hearns badly a while before the finish, and had totally changed the dynamic of the fight by that point, I don't think that one deserves a mention.

I'd have to watch it again, but seem to remember Gatti vs Ruelas would be up there?