This is like a very obvious thing to recommend since we're in Dollars, but oh boy, if you haven't checked out Durarara!! and Baccano! yet...
I don't really know much though I like the genre, but I'll mention some I know.
The Way of The Househusband is more of a slice of life comedy than a pure gangster thing, but man is it glorious. It's about an ex-yakuza being a househusband.
I've never read it but Gangsta is pretty well known? I heard it's good.
I'm sure you've heard of it, but Katekyo Hitman Reborn is a shonen series about a soon-to-be mafia boss. It starts as comedy, too.
Umm jotaro my dude all jojo art styles are sexy af. Jojo as its own entity is sexiness in its true form. Jojo poses are an art: a real example of beauty and elegance. Jojo is life. Jojo is soul. Jojo is religion.