Yeah, I agree with the other ones-
A simple cover is more pleasing.
Concentrating on one character has a nice feel to it. Maybe it doesnt look THAT exciting, but presenting the character right, and they can look quite cool & of course, you'll expect something interesting to happen with the character on the cover in the volume.
Bleach & World Trigger are good examples for these! Though, not a fan of Assassination Classroom's covers, it is very effective & iconic(I guess, I'm just not a big fan of Koro-Senseis face).
Black Clover have a few nice volume covers I enjoy(the one with Yami the most), but I also enjoy several covers of My Hero Academia. But in this case, it's different, bc here I like the volume covers which are clearly Superhero-comic hommages/references(don't know how to call them). For example, I mean the one with Deku / Ida versus Stain in the background, or the one where Deku fights Muscle, who shattered the actual background. That looked rad!
I also really like One Piece's covers, bc they're bright & colorfull. That is just nice! Though sometimes they're too full and there are too many things on the cover, but still.
