I want to say elise, just because of her leap, stun, and burst! Malphite's slow is pretty useful as well, but I favor elise for her utility. She also has a movement speed boost while in spider form, so that's useful!
Warwick. But only after 6. Run at them, press R, hope your laner follows through, win. Repeat. He's kiteable though so watch out for that while your ultimate is on cooldown.
Thank you for your responses My choice is Lee sin, I love to gank and murder people when I use him. He has the best ganking skills for me. First skill then 3rd then escape using the 2nd skill and boom! Anyway it still depends on the player using the champion
Lee Sin is very hard to play but can be a very good ganker if his combos are executed correctly. I like Elise, she has a lot of ways to get close to her opponent, making her a very "sticky" champion.
Any jungler that has strong CC is good for ganking. The one that's really strong right now is definitely Sejuani. Lots of CC (slows and stuns) and clears the jungle really fast.
Jarvan and Sejuani are the best gankers. Lee Sin is up there but he has a high skill ceiling and isn't recommended for certain players. I prefer Jarvan overall if I was going to apply heavy lane pressure, his combo is easy to do and he is a overall strong champion when it comes to team fighting.
CC is the way, Lee Sin is an obvious choice albeit a bit dangerous to choose considering he requires skill. Rammus can also teach you how to initiate well, and Vi is no exception either.
I think any Jungler with a huge gap closer is great to gank, especially in early. For example, I think Shaco is the easiest to gank on level 3, you can't possibly know where he is, and when he is going to gank which lane, and if you push your lane in the early game, there is a high chance you will get backstabbed then slowed with his E, and if he place his box in the right position, you are likely to be the first blood. Also, it is so satisfying for me to gank with Vi's Q.
I know it's been a while since you posted your question, but I will answer regardless. Now since Tahm Kench has been released, I feel there's really no other champion that can surpass him. It's really a monster. But we'll see the nerfs Riot brings in a little while.
Post-6, I'd say Rengar is the best to gank any lane, because well... he's Rengar and he doesn't care about wards. Same for Shaco. In terms of straight up killing the lane when ganking though, point-and-click CC is generally the way to go. My bet is on Vi, because if she ganks a lane you better believe that lane will either die or waste summoners.
Lee Sin takes a lot of skill to actually be useful so I wouldn't really recommend him for beginners. Evelynn and Shaco are much easier to pick up and if you can play and build decently well, you'll be able to either snowball yourself or your teammates very easily. Evelynn's really strong and annoying.
Elise is probably the best compared to difficulty. Pretty easy to play but can be very effective. As others have said, Lee Sin is probably the best overall, but comes with a higher learning curve and more difficult in execution consistently.
Sejuani and Lee Sin seems to be a common trope ganker. They have pretty strong stuns and jumps I doubt any other champion can compete. But yeah as said earlier Lee Sin is hard to master.
I think anyone with a hard CC is where it's at. No soft cc, no slow or snare - a stun or root is the only way to go. Anyone who fits this bill could be the perfect champion for ganking!
Xin. It's an essentially no-brainer champ. I feel it's very unbalanced since that E isn't even a skillshot one... I feel like Riot should really rework the champion a bit because it can easily carry games a lot.
Early game, Xin, Lee are basically unmatched. Elise and Sej during the mid game/late, also the likes of rengar post 6 are devastating.
For me, Xin Zhao because it has an incredibly powerful gap closer that really suprise you when you get hitted by me. Definetly for me it's one of the best ganker at the moment.
I don't know why you guys like Xin that much. I don't want to be mean, but he is simply too weak. Even in the early game he gets stomped by the likes of Elise, Nidalee and Lee. If he doesn't snowball he's useless.