I can't believe I'm doing this, but I'm taking Abdula's side...
Gaara isn't 'evil', he was just venting out anger. even without Naruto's medical treatment of head butting\punching he would have grown out of the killing phase at some age.

Had Naruto been able to kill some as a child, chances that he would have.
Naruto couldn't develop a psycopath frenzy becuase he could never do anything right, he wasn't a mistreated genius, he was a neglacted avarge joe. besides, he had Iruka by his side, and according to some flashbacks, some other friends as well.

favorite villian? Kabuto, since day one. spy, ninja, doctor, he's perfect. I wish he had more screen time.
Zetsu seems funny, but it's been a while since 'venus-flytrap-badass-dude' gave us something to be excited about.
I'm also kinda growing fond of Orochimaru.