Joshua by weight alone, The higher the weight class the more emphasized the statement "a single punch can change the fight" becomes.
For me AJ has the better chance of him winning his rematch ( I'm picking Usyk to win again BTW) rather than Canelo in his rematch. AJ has a chance in that he never really utilised his size, weight and strength attributes in the first fight with Usyk. AJ fought Usyk's type of fight for the most part. Not the best idea against someone of Usyk's talent. I will add that I personally thought AJ boxed better than I thought he could, and also AJ's gas tank lasted better up to around half way through the 11th round at a decent pace in general. If AJ goes all in at a risk of gassing or getting caught he still has a chance of catching Usyk. It's not a given that he won't. If he does catch him it could well be all over. As for Canelo, well I'm not sure what he could do any better at 175lb than he did in the first fight. For me I just think Canelo hit his ceiling as well as his boogie man in Bivol. I think Bivol's got Canelo's number and with Bivol's now improved confidence and self belief I think Bivol will win more convincingly next time. Maybe even stops Canelo. I think the best thing Canelo could do is forget the rematch and drop back down in weight.
Boxer-Puncher Joshua has the best chance in the rematch, IMHO. He can change his fight plan and turn it into a different fight altogether. I'm not predicting a Joshua win, but I am saying that Boxer-Punchers often do better in rematches, if they used the wrong style in the 1st fight.
Expect both to lose in the rematch. Joshua could possibly perform better with a more effective gameplan. No way in hell was he ever going to outbox Usyk sitting in Usyk's pocket and exchanging combinations. That's Usyks world. Can only see Joshua winning by stoppage. Think Joshua does have the power to hurt Usyk, although unlikely he does. Let's say he can keep Usyk at the end of his punches, on the outside, I doubt he can but he still needs the gas tank to make that work, which he doesn't have. Canelo had his moments, especially in the first 4/5 rounds, but unlike Joshua, he doesn't have the physical advantages to beat Bivol on the outside and didn't seem to have the power to hurt Bivol either. At least Joshua knew he lost unlike Canelo.
Joshua and bet on the KO, Usyk's own wife said he lost 10KG during the war AJ can really get a cuts stoppage at the very least if he just lets his hands go more.
They both have around a 30-40% chance of winning their rematches imo and id have them both as betting underdogs going into those particular fights.