I assume Noc isn't played more because he's squishy. Junglers tend to be initiators in fights, and need to be able to survive a few hits. Though, I suppose yu CAN build him pure defense. I Guess. --- "So selfish them" would be their cry. And, who'd be brave to argue? Doin' what you people need is never on the menu!
Not just to be different, but I'd say Cho'Gath. Even if you suck, your Ulti is going to make you pretty beefy at the end of the game. You have a ton of utility for your team, plus a true damage nuke which again needs no extra items to really do its job.
You can build him to be an immovable object. You can build him to do amazing burst AoE damage. He's very versatile and fits in with a large variety of team comps.
Plus his jungle is fairly fast and safe due to his passives. --- http://i.imgur.com/ZhLrT.jpg http://i.imgur.com/H6Frl.jpg
^If you're going to only play one jungler, play something intricate or high skillcapish. --- http://i.imgur.com/fiZMB.jpg http://i.imgur.com/TeSHa.jpg http://i.imgur.com/rBBQG.jpg http://i.imgur.com/xUh6r.png