I'm leaning towards Joyce but Whyte's left hook is one of the hardest punches in the division right now with Joshua's uppercut and Wilder's right hand and with Joyce's tendency to get caught I wouldn't right off Whyte at all. But Joyce is bigger, he's open for the right hand not really the left hook from what we've seen and Whyte's conditioning isn't always as good as it could be and I think against Joyce that could be a problem as he sets such a high pace.
Joyce would slap the head off Whyte White at best is really chisora level, which is decent, but he is nothing special He has been managed well and has a couple of good wins
Joyce has at least 2 inches more height, 2 inches more reach, 15 lbs more mass, faster feet, a granite chin vs a weak chin, an excellent engine vs a suspect engine, is mentally unflappable, has an excellent amateur pedigree, heavy hands and is undefeated as a pro vs 2 losses, one of Whyte's just a fight removed. We've seen Whyte get gifts against Chisora and Parker; he's on the that level just with a bit more skill than Chisora and more will than Parker, more power and reach but a far worse chin than both. Joyce would grind Whyte down and stop him comfortably.
Joyce late stoppage, but I'll say this. I would not be suprised if Joyce gets staggered badly by a left hook
I think Whyte would win easily but it looks like I am in a very slim minority. It's good to see difference of opinion and it would be even better to see this fight happen in real life.