[Akira]

There is no question that I place Berserk as my top favorite candidate. The story is just different, I love the soundtrack, fighting scenes are really nicely done, animations in general are superb, etc.

Second would definitely be Cowboy Bebop. In contrast to Berserk, the time it's set in is completely different, however, it still delivers a pretty captivating and the cast of characters is really good. Animations are also really good just like Berserk.

My third absolute favorite of thus far seen animes would probably be Arjuna. Again, the animation work in each episode looks like the quality of some movies and the original storyline kicks ass. Not exactly what you're looking for in terms of brutality but it definitely has the mature factor covered.

I would also like to state that I'm completely neglecting anime movies in this list seeing as the outcome would differ dramatically.