Originally Posted by
Yakisoba
Lee Sin definatly, You have Nocturne already and Udyr, both are very very strong. With Lee Sin you'll pretty have a trio of the strongest junglers in the game with Lee Sin personally in my opinion being the strongest champion currently in the game. Having this trio makes you very unbannable and you will always have a strong jungler available during ranked games. Lee Sin is banned commonly becuase he is so strong, Nocturne sometimes and Udyr pretty much never. Having this trio makes sure you can always bring the pain.
Skarner like you said is surely underestimated in his ability to be tanky and bring decent utility and dps mid game but compared to Lee Sin, Lee Sin is much much stronger early game, mid game and late game than Skarner is. Skarners ganks are also sub par compared to Lee Sin because Skarner does not have a gap closer like Lee Sin. Udyr is also stronger than Skarner as whilst Udyr doesn't have gap closer alongside Skarner, Udyr has a chain stun, his Bear Stance is such a powerful cc with red buff, Skarner has nothing like this except his 100s+ CD ultimate.
Lee Sin can counter jungle and counter-counter jungle(lols) extremely well because his HP during the entire jungle phase is kept quite high due to his sustainability of his shield and how fast he is at taking down mobs with his passive, this makes him fast and safe at his own jungle aswell as counter jungling. I have no comment on how well Skarner counter jungles because I have never tried counter jungling with him, I do remember getting counter jungled by a Udyr however and I did not have the hp in order to stop him stealing my large golems when we met up.
I'm not trying to make Skarner sound terrible I mean there will be good Skarner players who can potentially dominate a Udyr or Lee Sin in terms of successful ganks but that entirely depends on your skill level, I'm trying to pinpoint they're strength and weakness in general at one skill level (hopefully you understand what the hell I mean here, I didn't word it well at all)
Another plus for Lee Sin is he can solotop extremely well, being one of the strongest he surely counters many of the other SoloTops such as; Lee Sin counters Nasus, Jarvan particulary well, Irelia and Akali along with some others. I have no comment on Skarners ability to SoloTop as I have never tried it but I haven't seen it too often meaning it could be not that strong. Udyr is also one of the strongest Solotop laners in the game due to his survivability, in escaping ganks and sustainability in turtle stance and burst damage with tiger stance.
Another Jungler(s) who I would recommend alongside Lee Sin is Amumu and Gangplank, if you have Nocturne, Amumu, Lee Sin and Gangplank you will dominate ranked games as a jungler as they're pretty much the toppest tier of SoloQ junglers but all 4 of them are never banned in one game. Amumu has a gap closer with bandage toss he also has decent dps and one of, if not the most powerful ultimates in the game so far, Gangplanks slow makes him an amazing ganker and whilst he doesn't exactly have a gap closer he does have a ranged slow since his parley will apply his passive slow and red buff, gangplank also has a decent ultimate which can help teamfights as well as his ganking and raise morale is a decent utility buff for the team and I forgot to mention his Remove Scurvy removes all cc effects on him making his ganks very very strong aswell as his survivability in teamfights.
I'll address Yi aswell: Jungling Yi at ranked games and higher tier of play (personally I was 1900 in S1) is seen as the only viable way of playing Yi since he is a melee and solotop Yi isn't really viable against the others unless you play AP because the likes of Irelia, Garen, Lee Sin will destroy solotop AD Yi. Yi is a strong jungler, he has a decent gap closer with Alpha Strike and red buff makes his ganks viable and his ultimate with red buff makes his ganks a lot easier. He can be counter jungled quite easily however by counter junglers in the early phases of 1-5, at 6 he can probably just run away however.
Theres my wall of text with heavy editing on some of the junglers.
TLDR: Learn to read informative posts.