Death Note Vol.12 is one I can think of. Gives off a vibe that’s both haunting and a sense of finality, partially with Light’s pose in it in relation to what happens in the final pages.
Bleach Vol.19 is another one, I suppose. Really liked this series as a kid. The manga volumes usually give each character one cover to appear on, but this was the first one the where a character got more. It was also where Ichigo fought Byakuya and the former first performed Bankai.
Kagerou Daze Vol.1 had nice cover art, with the simplistic use of color, and the characters looking pretty cool. I ended up getting it for that reason alone. I really ought to revisit that manga again.