FMA and FMA: Brotherhood are nice because, even though they're mainstream, they still cover pretty heavy material like racism, genocide, the atrocities of war, sacrifice, progress and science vs traditions and religion, and so on.
Evangelion is also nice, though its really hard to tell if they're really being 'deep' or if they're just using iconic imagery and themes that seem deep, but really don't know where the hell they're going.
Beck: Mongolian Chop Squad is probably the best slice-of-life anime I've ever seen thanks to it being very down-to-earth about everything, though its not all that deep (other than things like corruption in the entertainment industry, but I don't think that really counts). Though it still manages to throw in some tasteful maturity, sometimes through tasteless immaturity.
I've recently gotten into Gankusuou: The Count of Monte Cristo, which is a strange little show about corruption in the fictional future French aristocracy, if that intrigues you.
I've also heard good things about House of Five Leaves, which I haven't gotten around to seeing yet but I hear it features some dark, unsavory things.
Evangelion is also nice, though its really hard to tell if they're really being 'deep' or if they're just using iconic imagery and themes that seem deep, but really don't know where the hell they're going.
Beck: Mongolian Chop Squad is probably the best slice-of-life anime I've ever seen thanks to it being very down-to-earth about everything, though its not all that deep (other than things like corruption in the entertainment industry, but I don't think that really counts). Though it still manages to throw in some tasteful maturity, sometimes through tasteless immaturity.
I've recently gotten into Gankusuou: The Count of Monte Cristo, which is a strange little show about corruption in the fictional future French aristocracy, if that intrigues you.
I've also heard good things about House of Five Leaves, which I haven't gotten around to seeing yet but I hear it features some dark, unsavory things.