Green Scar or stalemate. The idea that the Green Scar could amplify his physical attributes at a whim without going ape shit, clearly indicates that he is superior and the most powerful Hulk to have been written to date. That's just the technical side of things. As far as feats go, the Green Scar is heads and tails above Maestro.
Gotcha. Greenscar stomps. Not only did he beat some Savage Hulk peers that was amped a thousand folds with ease...he ate the power of 137 Hercules and shrugged it off. That isn't even his best. He overpowered the Mindless Ones with a leg and a hand and his thunderclap koed a being that was stated as being amped with enough power to shred earth...wait, he was said to be as powerful as 17.5 Hercules. Forgot to add that he ripped through Umar (who was feeding off of Dormammu power as well) barrier with a measly thunderclap. He dropped Loeb Rulk with a thunderclap after tanking a punch from him that made a nuke cloud...then he was weakened when he did this. His fts goes on and on and on. He dismissed the Avengers with a kick and told all of them that they were nothing to him, make room for his son, who had to amp off of 100 trillion tons of power of fight Hulk and he still got overpowered with one hand. Any other Hulk would lose but Greenscar stomps.
No he really doesn't, and it's not close. Here's why; Trauma was able to go toe to toe with the Merged Hulk for a decent amount of time, and his father Arm'Cheddon was able to beat the shit out of Merged Hulk. Maestro was a little more powerful than Arm'Cheddon during his on panel showings, while the Green Scar was holding back, and stomping the mess out of him. The thing here is that Maestro at base was about as strong as the Green Scar, but what makes this a stomp in his favor, is that he could go from base to planetary destruction in an instant which was shown in the Dark Dimension. Based on feats the Green Scar would destroy Maestro and do it rather quickly.You're going to have to come up with some feats, reasons, or showings to support your opinion, or not but at this time the Green Scar's showings surpass maestro's by quite a lot. You need to recall the plot meditation that he underwent on Sakaar that allowed him to amp at will without having to go completely berserk.
Green Scars best feats suffer from massive CIS but that aside its been the general consensus that most forms of Hulk are similar in power level obviously expect the more powerful versions that are trans level+. It isnt a stomp either way Maestro has less morality which will give him the edge in this scenario.
I would agree with you if they weren't going to fight in neutral territory. In a neutral territory, the Green Scar wouldn't have to worry about innocents getting in the way, and like Ii said, he is able to out amp any Hulk and do it at a whim. On Earth he held back the entire time. Maestro doesn't have any showing to date that outdoes his best performance, so for now the Green Scar was shown to be superior on panel. Maestro simply wasn't written to have the plot device amplifications at will that the Green Scar was written to have. This is the only reason that I favor Planet Hulk.
In this case it is a very good reason to give him the vast majority, because he has more fine control over his power set. He went from not being able to stop Sakaar from blowing apart like Krypton, to stopping it with brute strength in less than 3 panels or some crazy mess like that.