So yeah, this question has been bothering me.
Going by manga statements from Shin, Vegito Blue is stated to have possibly surpassed Beerus during the future Trunks Saga.
When Jiren shows up, it's heavily implied he's the one mortal stronger than GoD, which would likely include Beerus.
Then once UI Goku appears, he forces Jiren to get serious in a fight, and while he didn't win he did push Jiren more than he ever has been. I think it's safe to say UI Goku is at least at serious Jiren's level, if maybe not Jiren at fullpower.
So does this mean that UI Goku has overshot Vegito Blue? Logically, I just don't feel any individual form could be stronger than a fusion of said form's user and another powerful Saiyan. But going by evidence that's a possibility.
So what do you guys think? Is UI Goku above Vegito Blue?