Honestly in my opinion i love karthus jungle. its actually really fun and good! promise im not trolling either. i wouldn't mind helping you learn either.

Get Pantheon Olaf or Xin Zhao. In my opinion are really good Junglers.

For 3150 you can get Pantheon, at the moment he's pretty strong due to his ganking potential and mandrop. If you think you can handle a carry jungle role then get him.

Sources; I've been maining jungle since the end of S1.

irJebus wrote Yi isn't the best, but gets the job done.
Lee is great if you can land your Q's.
Pantheon can expect a nerf after LCS.
Kha'Zix is a great offensive jungler.
Vi is getting a nerf later on, but she is a terror in jungles.
Dr. Mundo is a great tank and has nice ganks.
Wukong has great ganks and great initiation in team fights.
Udyr is fun late game for tanking and doing damage. Great for split pushing.

You forgot Amumu [ Register or Signin to view external links. ]