According to EW, Professor Dumbledore is the best teacher EVAH:
ALBUS DUMBLEDORE (Richard Harris, Michael Gambon)
The Harry Potter books and films
SCHOOL Hogwarts School of Witchcraft and Wizardry
STUDENT Harry Potter (Daniel Radcliffe)
Dumbledore represents everything a good professor can be: a mentor, a father figure, and a friend. If it wasn’t for him, Harry would have never gotten over his broken past to become the wizard he is today. And really, who doesn’t love a professor who makes up words at schoolwide banquets? Cheers to Dumbledore for bringing the ridiculous back into education.
Also on the list: John Keating from Dead Poets Society, Indiana Jones (yes, he was a teacher!), and Mr. Hand from Fast Times at Ridgemont High.