I’d say give One Piece another shot, it’s long but it’s great the whole way through so it never feels like a slog.

Choujin X is a more recent one that’s super good, amazing art and interesting characters in a pretty mysterious world. It has an amazing first chapter and first volume in general, so give it a try!

Finally, I’d give Undead Unluck a shot. It’s gonna be an anime soon, but it keeps getting better and better in my opinion.

Hope that helps!