but it's absolutely boring to play them?
For me it's Nunu. Fun champ while I was (re)learning him, apparently my most played champion this season, I am extremely comfortable with and know the ins and outs of his kit, but I just kinda groan every time I have to play him.
It's really weird in that I have waaaaay more games on many other champs like Wukong and Master Yi in my entire League lifetime, but I'm still not bored by them. Every time the stars align and I'm allowed to play either of them, I jump on that chance and it's always great.
But then comes along Nunu and while he's basically my most reliable pick, and I'm not gonna drop him any time soon, I just feel bored by him.