Other than The End: Hulk I didn't read the others. I'm under the impression however that he was talked out of it. Isn't this three or more times that Thanos has had ultimate power and was defeated. Once with the Cosmic Cube, once with the Infinity Gauntlet (by the burned slow walking corpse of his granddaughter too) when he killed half of the universe, and again with the HotU. Each power was slightly more 'ultimate' than the previous, yes, but the pattern remains - Thanos and ultimate power don't mix.
Even the new Thanos comic admits it: "He’s held ultimate power in his hands, only to see it all slip away time and again. His attempts at conquest and destruction have all been thwarted."
A point of course is whether or not Doom would have this insight into Thanos' character, despite the fact that I think most heroes are aware of the Infinity Gauntlet series and the Cosmic Cube deal-y way back when.
Of course we are talking about comic books, my post was partly devil's advocate because everyone was voting for Thanos, and of course the third paragraph was kind of a rebuttal for my choosing Doom as the v/Victor (haha 😘).