I like slice-of-life stuff because I'm an easily stressed sort. I guess most of those aren't mainstream, except Kaguya sama, Bocchi and SpyxFamily.
My less popular picks (AFAIK) are: Acchi Kocchi, Kill Me Baby, Yuyushiki, My Senpai Is Annoying, Hidamari Sketch, When Will Ayumu Make His Move?, Asobi Adobase and Wasteful Days of High School Girls.