I use Fiddlesticks as my primary jungler, and msot people don't. But I don't really play ranked games. If they made me jungle in ranked though, I could see me chosing Fiddlesticks. He's extremely fast, clears the jungle at full health, can solo dragon earlier than most, doesn't need to start with cloth armor or health pots like most (so he gets a head-start, with an Amplifying Tome), and he has good ganks with his fear, ESPECIALLY after his ult which allows him to pop in from anywhere. I think he's an underused, underappreciated, and underestimated jungler.