If I can choose any anime, I'd choose the teachers from Ninjutsu Gakuen in Nintama Rantaro. They rock! Ohh, and since there's now an anime version, how about Yankumi from Gokusen! She is a fantastic teacher, and literally kicks butt. xd
Concerning Onizuka... I don't think the author means NORMAL TEACHERS. Look at that fuggin' list, ninjas and whatnot. Onizuka would be hard up to win, I mean honestly, he may be the Onibaku, but, NINJAS!? AND GENKAI!? Now, if it was NORMAL TEACHERS, Onizuka would own them all. But here, it's best to leave him out of it.