Trundle is my favorite jungler. He might not be the best with ganks, but his sustain is ridiculously good, and is an extremely helpful part of the team even when the laning phase is over. His ultimate makes you god tier tank, and lets you instantly shut down their bruiser or tank.
As for Nocturne, he used to be my favorite jungler until I found Trundle. Ganks are very dependent on his Q skillshot, and if they have flash they are guaranteed to escape from you. But at level 6, it's a walk in the park. The park of death.
And lastly, while I'm on the subject of junglers, I was playing some 5v5 normal the other day, wasn't paying attention, and got the last pick of the team comp. It was jungler. I didn't feel like playing any of my usuals, so I picked Darius. I loved Darius when he first came out, and stopped playing him for no reason. I had never jungled with him. The beginning was extremely rough, since I didn't know to start with armor and pots, and went with a vamp. scepter. But by the 20 minute mark I was 7/2/?. We would've won, if the support and carry didn't rage and give up on the game by selling their whole build and running at the enemies head first.