Both have a month of prep. They battle in a neutral dimension where both their powers work without flaw. Both at Full Power. No Reality Gem. No Cube. No IG. No HOTU.
Probably Dormammu. Cuz we've all seen what Doc Strange can do with some prep time. And Dormammu is quite the magic dude, if not quite up to the snuff of the Sorceror Supreme.
__________________ DarkCrawler is my hero... RESPECT LEONARD NIMOY!!!
Eternity was pissed that a mortal was even in his realm the first time he met Strange.
The Ancient One was the only Earthbased being he ever had communication with until Strange.
Eternity was a total dick until the next few times they met.
The Dread Dormammu is hella powerful magic entity.
I would say his powers are greater in scope than even Thanos.
Although Thanos could possibly outsmart him, but Dormammu
is practically indestructible. His weakness is his own arrogance.
Dr. Strange beats him by exploiting that weakness, not with powers.
Dormammu even had the nerve to go after Eternity.
Thanos would not try that without the gauntlet or something.
__________________ The whole problem with the world is that fools and fanatics are always so certain of themselves, but wiser people so full of doubts.
It's easy to say Dormammu for the win, but you can't forget that they both have a month of prep. That's an entire freaking month of prep for Thanos. I mean, power aside, he's actually taken over 616 several times, a feat the Dread One has yet to accomplish even once.
Sure, Dormammu's got tons more power than Thanos, being a mystical being himself. In this fight, that won't mean very much for simple reasons. Dormammu isn't going to spend a lot of his prep time wisely, certainly not as efficiently as Thanos. And there are very few people that can improvise like The Mad Titan on the spur of the moment. Dormammu isn't one of them.
I honestly don't think Dormammu would take Thanos seriously, seing as how he's not nearly as proficient in magic as Strange. Dormammu's ego would probably get the best of him, as it often does, and he wouldn't think Thanos would be worth exerting the effort to seriously prepare for.
And that would be a grave, grave error in judgement.
But still what is Thanos going to do? He has prep but what is he going to acomplish against pure mystical energy this powerful? When he had the Gauntlet he was still worried about Strange being a problem. Dormammu is every bit as proficient (if not more) proficient in magic as Strange. After all Strange used to call upon him to envoke mystical abilities.