Take this with a pinch of salt as I'm not using it as evidence or proof or anything like that, but Peter David who used to write the Hulk was once asked about how Thanos compares to the Hulk in terms of strength and said:
"I specifically(to avoid confusion) asked him if he thought Thanos was on a physical strength level higher than Hulk at any time he was writing(meaning various incarnations). He replied "Yeah, probably. Thanos is kind of in his own weight class." This is the guy who wrote Hulk for 12 years. Nuff said."
http://www.comicboards.com/hulk/view.php?rpl=990511190723
Again, not proof or anything, just throwing it out there, feel free to disregard 😛