While Looking for Zombie is cute and fun, it also has some dark moments. I checked MAL and it's listed as Adventure/Supernatural/Survival, with no comedy tag, but I view it as dark comedy. There are lots of silly things, but each episode has also had death in it in some comic ways and some serious. That's probably obvious in a zombie show, but I feel I should mention that.

I passed on Demon Slayer, as I'd read all My Hero and watched most of the anime, but eventually dropped watching it, as I'm not really into fight driven stories because people just have too much plot armor for them to be interesting for long, and am more into things that are just straight up jokes/gags and character driven stories now, and I figured Demon Slayer would be pretty similar but with demons instead of supervillians. Demon Slayer is still very plot armor driven, but significant characters do get killed off in impactful ways, the demon designs have been pretty awesome with some original seeming ideas, and the demons are former humans, so during and after fights, you get their backstories, which makes them much more interesting than just some random monster to progress the story, they are a big part of the story. I just finished an arc that was a bit of a look into how MC's life could have gone horribly wrong if things had played out differently and he had chosen the other path set up by episode 1, and there was a good look at the parallels of MC and the main villian of that arc that wasn't so apparent in the beginning of the arc. But other than the one sidekick character that I mostly can't stand, the show has been a pleasant surprise for a shounen.

Your comment about Chainsmoker Cat was along the lines of a post I read about it and that was what had me give it a chance. The characters don't really feel like they're being punished for being the butt of the jokes. All the characters are pretty likeable and relatable in their own ways. The jokes are all on them, but I don't feel it belittles them. Like you said, they just have really bad coping mechanisms. Despite all the gross and mean things most characters do, they still all get their good sides shown off too. Much of the gags reminded me of the same gross humor that Gintama or Golden Kamuy could do, but Chainsmoker Cat was just more about those gags than a deeper ongoing storyline. It was just total ridiculousness with, what in my opinion, where some of the best flawed yet likeable characters in one place.