Best jungler rn?

Depends. What kind of jungler are you and what rank are you in?

Of Leesin and Rengar, Leesin is better in general if you can play him.

That doesn't matter though, unless you're playing in high diamond and higher, just pick your favorite champion and that'll do.

+1 for Hec or Vi

Heca

I recommnd u to try heca he is nice jungler and can go even ender the turret and get his opponent. See some games on utube or streams

Actually Vi has the 2nd highest win rate (#1 is shaco but he getting nerfed next patch), and seems like a similar pick to your style. Hecarim is a great pick as well but riot said they will be nerfing him soon.

Just pick whatever jungler you like most.