Ali is bigger, stronger, faster, has a better chin, more reach, better boxing skills and has better footwork. Dempsey was great in his own era but he doesn't beat Ali.
Dempsey's more than capable of beating a fair few great Heavies, but not Ali. It's a terrible, horrible fight for him. He gets stopped late.
Dempsey was really just a Cruiser-weight by today's standards, so its a bit of a mis-match in size for a start. He came into the ring around the 190 mark (or there-abouts) which means he'd have been giving away at least 20 pounds to Ali. You could give the arguement that Dempsey beat big guys like Willard or Fulton both 6'6" but neither had the skill or speed of an Ali, so there's simply no comparison. Jack had problems with Tommy Gibbons and admittedly late in his career, was basically outclassed by Gene Tunney, the long-count of the rematch non-withstanding. This fight is a pure mis-match, as much as I love Jack, Ali wins this by comprehensive beatdown and mid to late stoppage.
Dempsey was 6foot 1 and a half inch tall. Manny Steward insists that Ali was 6 foot 2 and a half inches tall. We are talking one lousy inch difference in height. The clown talking about Ali's superior chin. Give me a break. Ali was K.oed by a 189lb. cruiser Henry Cooper. Yes, K'oed the fricking out. Dundee bragged for years how he sliced up Ali's gloves after Cooper put Ali in slumberland to give him time to recover. The immortal Jack Dempsey was knocked out of a ring and came back to win a heavyweight fight. Rahman had that happen to him and folded like a cheap suit. Fans who discredit the great Dempsey's reign of terror are idiots. Just ask another great; the mighty Iron Mike Tyson.
So what's your actual prediction on how the fight goes then? Rather than come in here to just discredit what another posters view is on how it goes, how about actually giving your own? Being a massive Jack Dempsey fan myself I dislike having to say it but I still believe Ali wins, and I wouldn't be surprised if you were in the minority in thinking that Dempsey wins this.
I agree Ali would win but Ali's boxing skills were mostly non-existant he relied on his speed and reflexes, he had no defence other than his reflexes, if you take Ali from actual boxing skills Dempsey was better in that area.