I don't see anyone ever talking about Hellsing. Why I enjoy it, it's edgelord but with a heart of gold. I love the factions that fight against each other in this secret war that involves the paranormal and vampires in modern day. It's got guns and magic and the art is good.
Another one I like is Ragnarok (into the abyss is the english title). It's a manwha by the korean artist behind the game with the same name. Again another little edgelord romp with a heart of gold, I see a pattern. Plus again I enjoy the art and it reminds me of old school 90's anime schlock with katanas and magic powers that I fell in love with as a kid.
Angel Densetsu is hilarious - a 90s comedy delinquent manga by the same mangaka who made Claymore (also a good read)
Devilman is the grandpa of all supernatural/demon horror stuff in japanese pop culture and it's actually really good. By far Go Nagai's greatest work.
Kaiji is great - almost as long as One Piece but it's a gambling drama that at least partially had a bone to pick with capitalism.
The World God Only Knows by Wakaki Tamiki is very good. He's a very good storyteller that can take weird concepts and make them interesting.