As much as I like them both, I would have to give this one to Doctor Strange. I mean, they are equal in magical ability, but Strange is experienced in dealing with MUCH more powerful villains and monsters than Fate is (the majority of Fate's villains, while powerful in the magic department, come up short compared to the likes of the crowd Strange tends to deal with, who are powerful enough and evil enough to make Discord at his worst look like a kindergarten bully by comparison)