GoodOmens said:
Exactly, DrunkNinja. Harry doesn't have the raw power of, say, Gandalf or Strange. He relies on the magical equivalent of sand in the eyes and a quick knee right in the tender bits. And summoning the occasional undead dinosaur.
Capcha: magical realism. Very well suited.
Bolded for emphasis. I would disagree that he doesn't have the raw power of Gandalf, as in the actual books, Gandalf never did much of anything except several light related spells. He was a glorified flashlight. xD Fighting the Nazgul on the rider, floodlight to the face. Banishing the spirit of Sauraman from the Rohan King, bright light to the face. In the mines of Moria, flashlight on his staff.
I'll grant Dr. Strange is pretty powerful, though I don't read his comic so I can't really compare, but I will stand by the fact that the thing that made Gandalf powerful, wasn't his magical muscle. It was his mind, and his ability to figure out the right bit of information to save the day. He was the one that went into the great library, and discovered the true nature of the ring, and thus knew how to defeat Sauran. Which is the key trait actually, that Jim Butcher quoted as being part of his inspiration for Harry, the investigator who will uncover your darkest secrets, and bring you down.
Though really, trying to debate which one is more powerful is kind of pointless. If you are crossing genre's and settings, the levels of power can vary drastically. In comic books, it's not a thing at all to have magic that lets a person summon giant tornadoes that shoot lightning and are possessed by some crazy demon thingy that also mind controls everyone touched by those winds. But in Middle Earth, that level of magical stuff just didn't exist. The magic was more subtle and pervasive, so trying to say one is more powerful than the other really fails at the onset, since they're working from entirely different playbooks of possible levels of power.