In an out-of-canon universe, the Avengers actually drive giant mechanized robots. In the story, they have to fight several popular Marvel villains after they absorb the power from the eye of the Kraken and become monsters. This includes Venom, Loki, the Green Goblin, and Dr. Doom. At some point, the heroes' mechs actually absorb the eyes as well and the robots become monstrous. The Avengers then have to fight their monstrous tendencies in order to battle the villains.
In Mech Strike: Monster Hunters #4 by Christos Gage and Paco Diaz, Dr. Doom grants Thanos an eye of the Kraken and the Mad Titan becomes a monster too. He goes toe to toe with the Hulk's mech, and Thanos is surprised at how evenly matched they are. They are so evenly matched that Thanos points out how he would never be able to match the Hulk's strength without the power boost he gets from the eye of the Kraken. This means that in a straight-up fight without the monster transformation or mechanized robot, the Hulk is stronger than Thanos.
The iconic scene in Avengers: Infinity War where Thanos beats the Hulk in a fist fight has tainted many fans' perspectives as to how strong each character is. The comics are a completely different story. The Hulk grows increasingly stronger the angrier he gets. Thanos fully understands this and so is aware that a rampaging Hulk is something he wouldn't be able to stand up to. This is an out-of-canon story, but it is a very telling admission for Thanos to just straight up say that he wouldn't be a match for the Hulk without a monstrous power-up.
That doesn't mean that Thanos isn't strong on his own. He is still capable of unbelievable relative strength to other characters in the Marvel Universe. But what makes Thanos so dangerous is not just his strength and durability but also his mind. Unlike the Hulk, he is a master strategist that utilizes various power-ups in order to level the playing field. Of course, his iconic Infinity Gauntlet is used regularly to boost his strength so that he could take on beings like the Hulk. In this case, he uses the eye of the Kraken to transform himself into a monster so that he and the Hulk can go toe to toe. But still, the revelation that Thanos is willing to admit the Hulk has more raw strength than him is something fans should take note of.
Mech Strike: Monster Hunters #4is now available from Marvel Comics