OK time for my prediction, I've gone back and forth but at some point you have to nail your colours to the mast right.
I'm basing this on what I see of both men in training, Joshua coming in quite lean and Usyk looks to be a little heavier to go for added power.
So here's how I see it.
Round 1-4
Usyk comes out early slightly aggressively minded but I thibk he will feel the power early, even if its on the gloves and switch up to fight more intellegently.
This will put Usyk into his usual habit of starting slow, working out the angles, Joshua will be a but quicker than Usyk expects and will win the first few low volume rounds by a few jabs a round.
AJ 40-usyk 36
Round 5 Usyk starts to work out the angles, he lands a little more, it's a more even round but hard to separate them
AJ 50- Usyk 46
Rounds 6,7,8
Usyk is landing the cleaner work, starting to pick AJ off a bit here, Joshua steals one of the rounds behind the jab, but Usyk takes the other two
AJ 78- Usyk 75
Round 9
Joshua realizes the fight is still up for grabs and Usyk is starting to take over, the boxing isn't going to get it done so he needs to take a risk, he comes out super aggressive (think klitschko round 3) he is getting a bit wild, Usyk clips him and Joshuas legs appear to wobble, he grabs Usyk, walks him back to the ropes then unleashes an uppercut on the inside, Usyk goes down HARD
The Ukrainian is tough though, he won't be kept down, he gets to his feet, legs are weak, but Joshua is beginning to tire, he has learned from his mistakes, he doesn't rush in and the bell rings.
AJ 88 - Usyk 83
In the corner, mcracken tells joshua to calm the eff down, he's 5 points up with the knockdown, get back behind the jab and keep it simple.
Rounds 10-11 boring shit with AJ behind the jab, Usyk being cagey, Usyk takes round 11, very low volume rounds
AJ 107-Usyk 104
Round 12, Usyk needs a ko, he comes out hard, he's willing to go for broke, AJ ties him up, there's a whole lot of hugging going on, the ref gets annoyed but Joshua doesn't care, the clock runs down, Usyk takes the round on aggression but he can't close the show on the bigger man who's committed to hear the final bell
AJ 116-114 or 117-113 Usyk
It's a closeish fight, but Joshua uses a combination of decent our boxing early, pure aggression mid way, and big-manning late to prevent the Usyk machine from working out the algorithm. Joshua gets some crap for hanging on to a small guy in the 12th round but nobody really wants to see a rematch either, and we move on to Fury v Wilder.
That's how I see it, folks.