Support junglers currently are the best pick, since they're safe. Propper ward coverage, can't gank or invade? No problem, you just have to hang on and wait until team fights, you're useful as long as you can release your kit once. Trust your ad carry to carry you.
Nocturne is a pretty good agressive jungler, but if no ganks are sucessful (really good ward coverage, enemy actively shutting down your oracles, enemy team has great safe picks with escapes and CC), then he just dies and becomes irrelevant in team fights. He's just way too risky.
Agressive junglers role has moved on counterjungling.
And counter jungling It's no longer a matter of taking out of the game the enemy jungler while becoming a force to be reckoned. No, it's a matter of forcing the enemy jungler to be worse than you, while you're already starved. And proper ward coverage will shut your game down even before you're able to buy an oracles.
I love playing Shyvana, she's my favorite jungler, but lately I have been tempted to move onto nunu. Even though he can't really kill the enemy jungler, he can take his camps easily.
If Shyvana has a bad game, she just explodes as soon as she tries to do anything.
If Nunu has a bad game, he just has to keep bloodboil on the ad carry and kite enemies with snowball.
Agressive junglers have certain good things still going for them, but they're just way too risky with little reward. Support junglers are just so safe that you can't really go wrong with them.