Cliche, but... Tyson. And if he fought better opposition more regularly, Wilder would be great fun to watch. I enjoy Dempsey, too. And prime Holyfield is a given.
It has to be Holyfield, done it? Look at this: Dwight Muhammad Qawi I Pinklon Thomas Michael Dokes Alex Stewart I George Foreman Bert Cooper Larry Holmes Riddick Bowe I Riddick Bowe II Ray Mercer Riddick Bowe III Mike Tyson I Michael Moorer II Lennox Lewis II Hasim Rahman And those are the ones I've seen, I'm sure there's other fun fights. Frazier, Patterson and Marciano are up there, but for me, it's always Holyfield. I think a better question is: "who is the most fun non-ATG HW?". Guys like Arreola, Golota, Brewster, Chuvalo, Bonavena, Quarry &c; could all make the list. I think it'd be pretty sick to see people list off their best fights and give me some new watching material.
Ruiz I also wasn't a bad fight BTW. For Ruiz standards it was a super exciting. Would you like to re-watch it and score to see if @Mendoza is right when he says Ruiz was robbed by the judges? I scored this fight 2 or 3 years ago and for me it was very, very close and depended on how you score the third round - 10-9 or 10-8 for Holyfield. If it's 10-9 round then IMO fight should have been called a draw. If it's 10-8 round then Holyfield won 114-113
For sheer excitement, I think Bob Satterfield warrants a mention. He went all out with his punches, could KO anyone, was explosive, but also had a weak jaw and so could get stretched himself at any moment. As an added bonus, he had pretty good technical boxing skills when he used them. Plenty of his fights on you tube.
I am a huge Frazier fan, but I would agree I don’t know if any HW was in more exciting fights than Holyfield. I might go Quarry with a non ATG candidate.
Ray "Windmill" White...Fought from 1958 to 1974....Lt Heavy & Heavyweight..he had long arms...he used to throw his right hand from behind his back. Used to see him on TV in 1971-1972. He's still around. He's 82. He was "fun" to watch!
Last of the great clown fighters. Nobody like him since. And he could fight, too. He was briefly rated as a Top Ten Light heavyweight.