Assuming we are talking about comic Dr Strange from before he got relentlessly beaten with the nerf stick. . .
Against Hulk, he should just plain win. Hulk is no more powerful than many other people Strange's defenses have casually bounced, and he can do all kinds of horrible things to the Hulk for which Hulk has no answer other than "Hope the writers bring me back in a future comic". There's just only so much a class 100 brick can do against somebody who views death as a polite recommendation and can use exploding planets as a method of propulsion.
Thor, by contrast, I'd say can probably take Strange. Its not so much that Thor is more powerful ( he's not ), its that Thor has an extremely powerful magical artifact that can both block/absorb magical effects, and deliver extremely high damage. Basically, as long as Thor rushes Strange and gives him no chance to do anything fancy, he should be able to bull through his defenses and hammer him in the face. If he hangs back, or waits, or whatnot. . . different story.
Basically, Dr Strange used to be the kind of guy whose rogue's gallery makes Thor's look wee. Strange's primary nemesis is Dormammu, whose basically Skyfather in power scale, and he isn't even the most powerful. Sure, Strange needs to use a lot of skill, cunning, and especially preparation to take on people this powerful. . . but the point is, he does, in fact, take on people that powerful. He may have needed to powerjack an elder god, borrow favors from Eternity, and transfigure himself into something only vaguely human to beat Shuma-Gorath. . . but those are all things he could do.
