I find Udyr and Mundo pretty good gankers actually. Sure, it's no Maokai which is pretty much guaranteed to be a kill if you are coming at any opportune time that your ally isnt on 5% and they are on 99% with 4 players in the bush. It all depends on your route and if you see them (your ally sees them, OH SILLY ME, and warns you about it) ward. But my favourite jungler is still Lee Sin, by a mile. His strong duelling and strong ganks early game plus the ability to safely counterjungle (ward+W over any wall) makes him a god. I've played a lot of Nocturne jungle before, and I feel Lee does worse at endgame than most other junglers (Udyr, Noct) so you should get your top and carry fed. Man, the plays I've seen from ... Diamondsomething from M5. So good.
But no, I generally try to focus on counterjungling (especially buffs) and ganking. I want to get my people fed, but if this really fails I'll take all buffs myself and try to carry. Saw Dyrus do this one game on Udyr, I copied this and actually managed to carry the game by flashmelting their AD carry every teamfight (went full tank with Wits, enough to kill AD carry). My mid would just lose blue anyway, and same with red on AD. I only focus on jungling on Shyvana, maybe Mundo, due to their insane movement/clearspeed, but I find it too boring. Unless you have a good mid to help you counterjungle/gank. TF <3
@above, I won a botgame yesterday in 14 minutes 30, one of my fastest ever. Was on Varus and had 27 kills by then with 12 assist BT + IE + normal boots. I like fast botgames.