Let me present to you: Guardian Lee Sin, the most broken countergank champion in the game
Most people go electrocute on Lee Sin, and then build him with duskblade and all kinds of stuff. However, I don't think they've even considered the power that Guardian has on Lee Sin. People run Guardian on Nunu jungle for the simple fact that anyone he uses W on, can proc it. Well, with Lee Sin, you have an even better synergy: Your W shield. It's actually so broken to gank via midlane by having your midlaner stand to the side towards the thin wall, and then you jumping over it just as the enemy goes in for a poke. The movement speed burst you and your midlaner gets is beyond broken, not to mention your W shield and guardian together negates any poke they would have dealt.
Now, to the actual runepage. My runepage looks like this in patch 8.4:
Boneplate armor is just amazing right now. In any ganks, if someone is trying to kill you during the gank, they can't. You're basically an unstoppable ganking machine. This of course works better against mid or toplane.
Conditioning gives you a minumum of 11 armor and mr by 10 minutes, which is equal to 450 gold or so. You're also going to be building some health, so it synergizes very well with it.
Revitalize is my personal preference, because I find unflinching to be kind of useless when you're dashing around so much anyway. And overgrowth is only good for scaling, and Lee Sin is an early game champion. It does increase incoming heals and shields as well as your own shield, and it works with guardian.
The second rune page is a no brainer. Every gank, you open by using W, which is a dash, giving you 10 free lethality. Relentless hunter is in my opinion the best rune altogether for any high pressure jungler, for the same reason I take mobis.
My build looks a bit weird, but hey, you gotta get those ward hops from somewhere, now that the jungle warding item is gone:
This gives you a ton of health, armor and damage. Of course, any item is optional, but I have yet to play a game I didn't get fed enough to build what I wanted. And of course, the targon's on first back gives you the option to camp lanes more and be more proactive, because after every gank, you get to take like 100+ gold back with you into the jungle, without stealing a single cs from your laner. And after 15-20 minutes, you get a great vision item that gives you ward hops for days.
You don't have to like the build. It's probably not the absolute strongest. However, I think it's a solid alternative, if your team needs you to be a bit tankier. I also think this build scales a lot better into the lategame than the assassin build does.