Starlin is a big fan of Hulk. People's perception of Thanos is skewed by a lack of context.
During IG both Hulk and Thor beat down Thanos before he used the IG to shrink down Hulk and later turn Thor into glass. The so called pimp hand, when Thanos primed a nuke and thus Hulk and Drax couldn't attack further, is always shown, those scans however rarely are.
Nor are the scans in which an amped Gamora beat the tar out of Thanos during Warlock And The Infinity Watch 8 or indeed the scans during Thanos' infamous fight with Odin in which Odin states Thanos is using a power source i.e. an amp (Warlock And The Infinity Watch 25), thus explaining why Thanos was able to fight Odin evenly for so long.
Thanos is obscenely powerful but he is not more powerful than either Thor, Hulk, Hyperion or Gladiator. He's at their level, as his fight with Thor during Infinity showed. Neither of them were actually hurt, albeit Thor was knocked down twice.
Thanos' best showings are thrashing Silver Surfer, BRB and Black Bolt. His best durability feat is tanking a black hole that pulled in everything from 2 light years i.e. 12 trillion miles (Infinity Abyss 1 & 2). As impressive as that sounds Hulk tanks a blast from an anti-matter canon (Tales to Astonish 78) whereas Drax used anti matter to kill Thanos (The Thanos Imperative 3) and tanked a blast that destroyed an entire universe (Incredible Hulk 126), superseded by Hyperion tanked the death of two universes but whose counting?
I doubt there will be a decisive winner. They'll brawl then Thanos will talk Hulk out of continuing or Hulk will get bored. I imagine it will be more of an actual Hulk & Thanos team-up to stop Blastaar and Annihilus.