Speed advantage, strength enough to overpower him ...
Ripping his head off via awesome super-speed neck-break twist sounds awesome and would work just fine, assuming you don't start him off at "I'm already ridiculously angry".
Wishing Well incident with Red She-Hulk?Whats the boards opinion on Hulks planet busting feat when he went world breaker?
I think him being a Planet Buster at his absolute best is - more or less - accepted.
But again, he needs either be extremely angry to do so, or his potential needs to be unlocked by an outer source (like during the Wishing Well arc).
Both isn't going to happen in a fight with Thor without Goldilocks dispatching him first.
Nah, outside of a couple of specific arcs, either dealing with external amps or with literally years of built-up anger, Hulk takes time to get to his max. And, as stated, his max requires really limiting circumstances. In a Rumble, the OP can say just fine "Hulk starts out at his Wishing Well max" but that's not the default, and even in such a case, Thor is still stupidly, ridiculously faster than Hulk, easily fast enough to blitz and break his neck, go all "Puny Hulk" on him, or drop him into the heart of a star.
This. Thor is still dozens of times faster and has, effectively, all the time in the world to do as much damage as he wants to. Even without the hammer, and without BFR, he could simply dash up, break all the fingers on one of Hulk's hands, then dodge the slow-motion haymaker, then break all the fingers on the other hand, then crush all the bones in one foot, then the other, now the elbows, now the knees, now the neck, now just keep twisting 'til the head pops off. Or just force his hands into the brain-case through the eye-holes. Hulk has a healing factor, and it's impressive, but it's not instant - Thor can keep doing more damage than Hulk can heal from, and Thor has a feat for fighting constantly for 9 months (solo against all of Jotunheim) without food, drink, sleep or rest.
To be fair he wasn't amped, he was just given the key to his full potential.
During the Arc he was able to, like Matt put it, go Super Saiyan anytime he wanted, but as you said, he doesn't have that kind of boost in his ordinary incarnations and thus becoming World Breaker would require a considerable amount of time.
Time Thor, even if he doesn't blitz, won't give him, due to his huge strength advantage in base form.
Within the parameters that we discuss rumbles here at CBR, you are absolutely correct.
However, as a long-term Thor fan (going back all the way to the early '70s), I am unable to recognize Marvel's Thor in your paragraph above. It's true that Thor has several scattered high-end speed feats that support your description, but his overall long-term presentation as a character has been nothing like a speedster. Thor almost never wins fights based on speed, he wins based on strength, skill, power, tactics and a plot device hammer, but not speed. I like to think that the occasional speed feats are weird functions of Mjolnir's powers and not something inherent to Thor's personal capabilities, but I have no definitive canon evidence to present, and it wouldn't matter from a practical standpoint here. But such an interpretation would explain how Thor can travel at FTL speeds and casually deflect bullets (that he should be tough enough to shrug off anyway) and yet receive blow after blow after blow from big, slow bruisers like Hulk, the Wrecker and Ulik.
I was under the impression that the rebooted Rumbles board started fresh with respect to certain past rulings like Thor's speed, but I haven't been around consistently enough to see where we stand now on Thor. Apparently he is currently recognized as having some level of superhuman speed, but hopefully he is still considered less speedy than Quicksilver.
Thor's speed was one of the ones that stayed static. As fast or faster than Spiderman, slower than Quicksilver.
Going to also point out that you just described PIS to a tee.