WW Hulk/Green Scar without a moments doubt. He was literally able to strength amp at will. It took him less than 5 panels to go from not being able to save Sakaar, to overpowering Sakaar's imminent explosion (Rogol Zaar eat your heart out type shit).
Mindless Hulk would have a better go at it with War Hulk.
Mindless Hulk has done some crazy crap. Like punching Onslaught so hard, he knocked his reality warping powers out of him (the writer even admits this). Him physically crushing Onslaught when a far less powerful Onslaught treated Classic Jugs like fodder. Hell, Onslaught with a pinch was able to snatch the gem clean out of Jugs. Onslaught was as powerful as both Franklin and Nate combined when Hulk beat him. Uber ft, but, WWH intestines was able to withstand the power of 100 Hercules. He beat 2 physical Herald level characters that was amplified a thousand folds. Tanked a blast that blew a chunk out of the moon the size of a state. Knocked out a being who had a portion of the power of an abstract. Pulled a planet twice the size of Earth together while weakened. Took on and defeated the most powerful version of Sentry "during that time". Withstood Zeus lightning... brushed off the Avengers (including Thor) with just a step of his ft and basically told them they were nothing and cant do anything to him, so step aside and make room for my son. Overpowered his son with one hand who just amped off the power of 100 trillion tons of force. Undecided and this thread is giving me a headache.
Well, It was actually written that the Green Scar personality was the most powerful Hulk personality up until that point in time. Most likely of all time.
Going into feats becomes a bit redundant. It isn't needed in this case, because one Hulk personality was pure out of control power, while the other could access an exponential amount of power on the spot, and do it at will. He didn't take any time at all to overtake anything that the Mindless Hulk showed on panel imo.
Breaking Onslaught's armor is a decent feat to be certain, but then again, so is taxing 1/2 of the Inbetweener's power. 😗
Mindless Hulk is when he doesn't have Banner curtailing his abilities so he can unleash more than usual, but Banner is also the fuel for his strength to grow since green Hulk is just a manifestation of his mind as the other Hulks are. Mindless Hulk weakens over time without Banner instead of amping steadily with him in the mix
Green scar is when Banner and Hulk are in sync and enraged without an internal struggle