Which band took the longest to grow on you? I can't name anything top of my head but it's more like I get a sudden epiphany about a band I have neglected. It's mostly about being in the right state of mind
Yeah I've had those "epiphany" moments as well, but occasionally I hear some music that interests me but that I don't think I'm fully grasping yet. That's when I'll usually put a bit of "work" into trying to appreciate that music and trying to see what it's all about. Happens more with genres or subgenres than with individual artists / bands / whatever tho.
Merzbow and noise music in general took me a long time to get into but it was mostly just about getting used to the volume.
King Crimson and Godspeed You Black Emperor (speaking of "post rock" lol) also took a long time to "click" for some reason. OTOH, I loved "Trout Mask Replica" by Captain Beefheart pretty much from the get go, which is kind of infamous for being supposedly "inaccessible" so idk.