100% agreement on this and I came here to say the same thing.I went with Monk. It is a somewhat underpowered class that makes up for much of its underpoweredness with the stunning strike feature, which is powerful but in a fun-breaking sort of way by trivializing solo enemy fights while also not being a very exciting way to use your ki. So underwhelming, but with one overpowered feature that gives the DM a headache without really being that much fun.
It's also just not my jam on a core thematic level. I'm not a hardliner against it by any means, but making it a core class such that every setting has to accommodate both a bunch of fantasy pseudo-medieval stuff AND this one random kung-fu interloper or else put the DM in the position of having to say no is just not something I've liked in any version of D&D that makes it a core class.
I might argue for the Ranger or Sorcerer having graver design missteps, but I enjoy those classes more overall, I just think they have frustrating progression and some obvious design blunders.
But, lets not overstate this. Even my least favorite class is not one I consider bad.