Which of those boxers will be Anthony Joshua's most challenging / toughest opponents?

I disagree. Wladdy is skilled and powerfully but he's not really full of surprises. He limits his offensive output and the types of punches he throws to protect his chin. And he's not exactly quick. Wilder is much quicker and more athletic. He also throws a lot more punches from angles people who worry about getting knocked out wouldn't throw them from (for better or for worse). I think he has a better chance of catching Joshua with something he doesn't expect especially early in the fight before Joshua gets into a rhythm. Wladdy is skilled and powerfully but he's not really full of surprises. Define 'surprises'! He limits his offensive output That's because every punch he throws and lands, usually has greater power than multiple punches that other boxers throw and land. It's quality over quantity. Hence, 1 Wladimir Klitschko punch > 3 punches from other boxers. and the types of punches he throws to protect his chin. Protecting one's chin is something one should always do if they are a defensively responsible boxer and that's a good thing. That doesn't mean his punches are any less effective and dangerous because he protects his chin when he throws his punches if that's the point you were trying to make. And he's not exactly quick. Wilder is much quicker and more athletic. Wladimir Klitschko is quite possibly one of the fastest super heavyweights of all time at 6 foot 6 inches in height and above 240 pounds in weight. Deontay Wilder may appear faster than Wladimir Klitschko, but it doesn't necessarily mean he is much, if at all faster than even a old Wladimir Klitschko. That's because Wilder throws his punches wildly and widely like an amateur swimmer splashing in the water with all their energy as fast as possible making their movements appear faster than a professional swimmer who's movements appear slower but enables them to cover a longer distance whilst using less energy and whilst making them appear as if they aren't moving as much. In other words, Wladimir Klitschko moves fast without appearing too fast because he uses less energy and moves with better technique that enables him to cover a specific amount of distance very fast without appearing very fast. On the other hand, Deontay Wilder moves fast but also appears very fast because he doesn't move with technique that is as good as Wladimir Klitschko's. He covers the same distance as Wladimir Klitschko taking the same amount of time but appears faster because his movements are less efficient. He also throws a lot more punches from angles people who worry about getting knocked out wouldn't throw them from (for better or for worse). Which is more of a detriment to him than a benefit because he isn't very defensively responsible when he does so and leaves himself wide open to getting punched by a skillful boxer like Anthony Joshua. He may get away with such punches and moves against inferior level of opposition but not against the absolute best boxers the heavyweight division has to offer. I think he has a better chance of catching Joshua with something he doesn't expect especially early in the fight before Joshua gets into a rhythm. I disagree and don't see Wilder having a better chance of landing anything more dangerous than what Wladimir Klitschko was able or incapable of catching Joshua with. Wilder has taken multiple rounds to stop / KO opponents after he stepped up in competition against better level of opposition who still aren't anywhere near as good as Joshua or Wladimir Klitschko. So the chances of Wilder knocking out Joshua early is lower than the chances Wilder had of knocking out Gerald Washington, Chris Arreola, Bermane Stiverne (First bout) and Eric Molina early. If he couldn't KO them early, then his chances of knocking out Joshua early is even lower because Joshua is a better quality opponent than any of those boxers.

Wilder would be the most difficult or the easiest. I think this is a fight in which either Wilder's speed and unorthodox punches catches Joshua before he gets into a rhythm or Joshua withstands the initial barrage long enough to take advantage of the openings Wilder will give him. I doubt Wilder's chances of knocking out Joshua is any higher than the chances that Wladimir Klitschko had of knocking out Joshua. And Wilder doesn't have the sufficient punch resistance either. Probably even worse than Wladimir Klitschko's and has significantly inferior boxing abilities in comparison. Someone with a good combination of punch resistance, punching power and technical boxing skills is going to stand a much better chance at beating Joshua. I'd say that Alexander Povetkin, Luis Ortiz and Kubrat Pulev will all have the greatest chances of beating Wilder.

Parker, Ortiz and Wilder

Wilder due to his erratic power punching. But i still make AJ favourite. This. Povetkin looks a better boxer but maybe time is catching up (or his previous power was assisted). Whichever he may have the technique to trouble AJ but not sure he still has the power. So Wilder, then Povetkin, then maybe Parker edges a fading Ortiz. Don't think Haye has enough left in the tank but on past accomplishments / hitting power he can be next. Pulev next then Miller last.

Wilder due to his erratic power punching. But i still make AJ favourite. If Ortiz still looks fresh and young and beats Wilder then he could have a great shout as well. If I could get a look at Usyk as a proffessional HW, and he can effectively uss his speed and accuaracy like he did at SHW in the WSB, then he would be a big test aswell

I voted the Windmill of Doom is the most likely to beat AJ because of his speed, power, reach,good work rate and stamina and a very good left jab.