I got the most entertainment out of Fred and George Weasley. Honorable mention to Luna.
It also always irritated me, when he was sent away or exiled from Hogwarts, how his allies kept saying he had to return to protect the students. Plenty of students were hurt or killed while he was there and actually on the job.
The historical record shows that from 1942 to 1995, exactly two Hogwarts students died on campus: Moaning Myrtle and Cedric Diggory (and technically, Cedric died in a cemetery in Little Hangleton).
ETA: Also, Neville turns forty this year. He might make Headmaster yet.
Lupin. Though I don’t find his relationship with Tonks plausible since I believe they’re both gay.
Go Neville!
In Half-Blood Prince, Dumbledore as good as allowed Draco to nearly kill Katie Bell without the slightest concern for her life.
There are lots of great names above that can’t be argued with. But what about the poor Hufflepuffs? Nary a word has been said about them and let’s face it, most of us would probably be Hufflepuffs! Therefore I nominate Cedric Diggory! Despite not being “brave”, “brainy”, or “cunning” he still won the Triwizard Cup, and was willing to share information proving collaboration is better than competition. In the end he was just the spare.