Texhnolyze, Higurashi no Naku Koro Ni (somewhat bi-polar though), Rurouni Kenshin: Tsuiokuhen, Soul Eater, Viper's Creed...
Not all of them are especially gory but relatively good action/mind **** anime. While Higurashi can go from happy sort of kid show scenes depicting school life, fun and games it quickly switches to some rather crazy over the top violence (which resulted in the second season being heavily modified because of pressure from japanese media) like: The opening scene where a young man beats two class mates to death with a base ball bat, or the start of episode 5 where a young girl slams her head against a kitchen knife repeatedly till she dies.Texhnolyze best fits your particular description but is also comprised of *********** present in Serial Experiments Lain (as it is done by the same people). Rurouni Kenshin: Tsuiokuhen or Trust and Betrayal are excellent and I would certainly suggest watching them if you haven't. Viper's creed was relatively good, with a decent amount of action. Soul Eater is the best long running shounen anime I can think of, no filler, not continuing story indefinitely for the sake of more money, doesn't devolve into DBZ (looking at you bleach), with a decent amount of comedy, large portion of action and an art style that was mildly reminiscent of Gurren Lagann yet strikingly unique at the same time, definitely worth sitting through 52 episodes of it. Kirby already suggested Black Lagoon which I will reiterate... Watch it, third season should be coming out soonish (this year sometime hopefully). Kirby also suggested Kara no Kyoukai... Put this on the top of the list as it's only real competitors for best anime I have watched are Haibane Renmei and Tsuiokuhen (that I can think of off the top of my head).
Texhnolyze, Higurashi no Naku Koro Ni (somewhat bi-polar though), Rurouni Kenshin: Tsuiokuhen, Soul Eater, Viper's Creed...
Not all of them are especially gory but relatively good action/mind @#%^ anime. While Higurashi can go from happy sort of kid show scenes depicting school life, fun and games it quickly switches to some rather crazy over the top violence (which resulted in the second season being heavily modified because of pressure from japanese media) like: The opening scene where a young man beats two class mates to death with a base ball bat, or the start of episode 5 where a young girl slams her head against a kitchen knife repeatedly till she dies.Texhnolyze best fits your particular description but is also comprised of mind@#%^ery present in Serial Experiments Lain (as it is done by the same people). Rurouni Kenshin: Tsuiokuhen or Trust and Betrayal are excellent and I would certainly suggest watching them if you haven't. Viper's creed was relatively good, with a decent amount of action. Soul Eater is the best long running shounen anime I can think of, no filler, not continuing story indefinitely for the sake of more money, doesn't devolve into DBZ (looking at you bleach), with a decent amount of comedy, large portion of action and an art style that was mildly reminiscent of Gurren Lagann yet strikingly unique at the same time, definitely worth sitting through 52 episodes of it. Kirby already suggested Black Lagoon which I will reiterate... Watch it, third season should be coming out soonish (this year sometime hopefully). Kirby also suggested Kara no Kyoukai... Put this on the top of the list as it's only real competitors for best anime I have watched are Haibane Renmei and Tsuiokuhen (that I can think of off the top of my head).
I've tried to watch Higurashi but it's so ugly I just can't stand it. And I've been reading the Soul Eater manga, watched Black Lagoon too (and awaiting S3). Going to check out some other names in the post and figure out if there's anything I want to watch.