Black Lagoon is by far the best violence anime I've ever watched.
It's both whitty and serious at the same time even though they are constantly in tough situations.
The dark humor alone makes this an anime on par with the greats.
I HIGHLY recommend watching this, the OVAs and the 2nd season because, lets just say, its god damn amazing.
The only problem I've noticed with Black Lagoon is that it lacks chracter progression for everyone exept Rock, but i guess living in the most dangerous city in the world would do that to a guy.
― Sun Tzu, The Art of War