tbh I can't remember all the slice's I've read over the years, but I stopped reading them until the other week when I read Oyasumi Punpun and really enjoyed it.
Btw thanks for the recommendations so far guys, I'll read some this weekend when I have free time and report back here what I think of em.
Okay, so, I'm just going to lay on several from my reading lists:
Ever Green - More about friendship than slice of life. Disclaimer: I'm not all the way through the story and have only been reading along with the English release.
Genshiken - There's 2 segments to this series. They both revolve around the same college club. This first segment ran from 2002 to 2006, and the second segment ran from something like 2011 to present. Maybe a bit longer than that, actually. There are a ton of references sprinkled into the dialogue and into the background, but mostly the dialogue.
A.I. Love You - This is more harem romcom, but it's fairly self-aware and keeps its core cast pretty small.
https://myanimelist.net/manga/13001/K-On - If you've seen the anime, you may not enjoy this so much because that will elevate your expectations since part of what made the adaptation so great for many was the soundtrack and concert scenes, which the manga lacks, but this manga is the source material the anime was adapted from. K-On! is a series where you'd probably want to read the manga first to get the most enjoyment out of it. It's also only 4 volumes long.
Related to K-On!:
K-On! High School - Follows Azusa in her last year of high school. It's all of 1 volume long.
K-On! College - Follows the other 4 girls to college. It's all of 1 volume long.
Love Hina - This is undoubtedly a harem romcom, but it's arguably among the genre's classics and was crazy popular while it ran (sold 16 million copies on a 14 volume series). Nisekoi's central plot device was kind of stolen from here, but Love Hina is over with in half the time Nisekoi is. And even less time is spent on protagonist waffling.
Mysterious Girlfriend X - This one's a bit odd, since it centers around drool, but if that hasn't deterred you, go give it a try. It's definitely not for everyone and one of the complaints had about it was that the pacing was super slow, but those people were reading it while it was releasing, and it was on a monthly release schedule.
There's more I'd like to recommend, but I tried to keep the settings to normal towns without much in the way of supernatural stuff. I also tried to keep stuff I scored a 6 or lower off of this list, since 6, while "above average" indicates that the series didn't do a whole lot to stand out for me, only just enough to not earn an "average" (which is still better than bad).