I'll be the casual fan who just goes by the Cinematic versions of each universe.
It seems to me the most powerful power in either Cinematic universe is Dr. Strange's ability to see/affect millions of possible universes. That IMHO puts him above someone like Dr. Manhattan from the Watchmen movie universe, who could SEE futures but had limited ability to change them.
If we're going with the implication that *everyone* has at least some Force sensitivity, once Dr. Strange learned that the Force existed he should be able to use the "Groundhog Day" effect for a couple of hundred lifetimes to level up his own Force abilities.
When I started typing this out I was all set to say that Dr. Strange's future prediction ability is far greater than Emperor Palpatine's, but I admit I'm starting to have the nagging doubt that we don't really know the extent of Palpatine's powers based on what we've seen on screen. In RoTJ he was constantly bragging that everything that happened exactly the way he foresaw. So its *possible* that he's not bragging and he manipulated everything down to the last second through Eps 1-3, Rogue One, 4-6 in order to create a SuperSith called Darth Luke after frying him with Force Lightning, and it only didn't work because of the 1 in a billion shot that Vader's "Balance Prophecy" would kick in at that moment.
But other than that possibility, I'm going with Dr. Strange.