I was hating lee too but then i play him!
and let me tell you why people play him so much
Simple because he is fun and not he is not OP i mean VI hecarim yi zac and many other champs are doing better
The "problem" that many people have with lee is that he is too flashy well that point of the champion
And trust me when i start playing lee i was like "f@ck all this right click champions" when i outplay them because all they do was AA and hope it feel good and that why many people have hate towards lee because he outplay every AA and HOPE champion and that GREAT because the last thing i want is to see a yi going in and AA and say "it skills man" gtfo from here
Yeah many of you will check my account and say "oh you play xin" no i play xin since he came out i have plauy xin for years because he was the only champion that he was a true WARRIOR and xin have go From OP to uselesness to normal to OP to useless again and now its "normal" (unless you are silver then he is OP for you) anyway that why i still play xin
So anyway lee is fine....if you stop playing AA and hope champion you will see it
And yeah if you sejuani jg guess what you will get counter jungle but not only from lee but from the 99% of the jungler champions sorry but sejuani is useless atm so your fault that you pick her...even if you main her if someone pick shaco on the enemy team and you pick naut on jg dont say "omg shaco so OP he stole all my jg wtf rito do something about naut so he can stop shaco in jg" NO tanks are mean to be weak early shaco is meant to be strong early (shaco is an example idc about his balance state to be honest i dont play him)
So anyway try lee and you will see that he is fun and feel good to play him