Plant by a small margin,he was better at keeping Canelo at bay, thus lasted more rounds,I think Plant won 3 rounds,Saunders did the similar thing so it's close
At the end of the day they both got stopped, and neither of them looked that close to really troubling Canelo - certainly neither hurt or backed him up which is necessary to nullify his 'chop down the tree' stategy he has adopted since GGG II. So IMO, it's a meaningless wash.
Now I’m going to risk a bit of ridicule here but Golovkin apart the fighter who’s troubled Canelo most in recent fights is Amir Khan. The way that fight ended in such a brutal KO for Alvarez often overshadows how well Khan had fought up to that point. He had really troubled Alvarez, hitting him with everything he threw including some meaty power shots that had Canelo going backwards. As the fight wore on it was Khan slowing down due to the constant pressure and threat that won the fight for Alvarez, just as much as the left hook that actually KO’d him. Credit to Khan for that performance, coming up 2 weight classes to fight the best in the world and an all time great
I preferred what Bill did, for as long as he was in there. He was actually engaging in a back-and-forth chess match with Canelo and outmaneuvering him by turns, but got taken out of the game by one especially effective play, whereas Caleb was more reliant on capitalizing on Canelo's management of energy.
I thought both BJS and Plant proved their heart as fighters. Neither had any real firepower to keep Canelo at bay, but they fought valiantly knowing this. I have more respect for both afterwards. Hard to pick, but I guess I'd go with Plant because his performance exceeded my expectations while I assumed Saunders was closer to Canelo's level.