The Only Sane Man is something a pet peeve trope to me, I almost find that it include character who either like daria, Kyon, Huey Freeman or Chisame Hasegawa.I think it is not the trope that annoys as much as the characters who invoke it are and nobody likes a jerkass. Are characters who are the only sane man without being jerkasses or snarkers?
"I'm always just going easy, you see?
I won't go easy on you in an official duel."
Well, for me, Chisame and Kyon give off more of a Deadpan Snarker vibe than a Jerkass one. In Chisame's case, she's more apathetic than anything, just trying to be normal even though for some reason she's surrounded by craziness.
Honestly, she's my favorite character in that series, as is Kyon in his.