LOTR guy: Meh, Gandalf is better.
Marvel guy: I cant seem to remember any real magic being preformed by Gandalf. I could do everything he did, if I had a flashlight and a beard.
Harry Potter guy: Dumbledore is the best.
other two guys: …… Leave our presence.
Magic: Dr. Strange is the Sorcerer Supreme of Earth's Universe; he has unparalleled mastery of the mystic arts, which he uses to defend his reality from otherworldly threats; his primary magical patrons are a group of entities known as "the Vishanti." The Vishanti are a trinity of godly beings comprised of Agamotto, Hoggoth, and Oshtur. Although he has, on rare occasions, called upon the power of demons such as Dormammu; Strange more frequently did so before he realized Dormammu's true dark nature in the earlier issues. Doctor Strange is potentially the most powerful being on Earth and one of the most powerful beings in the Universe. He has once stated that he can kill a mortal with the mere twitch of a finger. Eternity, the sentience of the Marvel Universe, has described Strange as "more powerful by far than any of your fellow humanoids", narration has described him as "the mightiest magician in the cosmos", and the Stranger considers him on a level with cosmic entities.
Source: wikipedia.org/wiki/Doctor_Strange; marvel.wikia.com/Stephen_Strange_(Earth-616).