Need Some Advice on Some Anime.

[Seydaman]

Mahou Shoujo Madoka Magica
Watch that.

Otherwise:
Steins;Gate
Shiki
Clannad (With Afterstory)

 

[Mrkillhappy]

Fullmetal Alchemist: Brotherhood

Samurai Champloo

Welcome to the NHK

Gurren Lagann

Eureka Seven

and another second for these
I'd also like to add
Code Geass
Lupin the Third
FLCL
Attack on Titan
and Trigun

 

[RejjeN]

So.. did I not see Hunter X Hunter? well then... ahem, cough cough,cleary-throat noises...
You should really really watch Hunter X Hunter!!!
I'm not entirely sure how to even put the series into words, really good looking animation, amazing characters, anyone can die. It has a dark story, yet light moments, and can really make you feel sympathetic to terrible monsters. not to mention the opening song is catchy as the clap.
I am talking about the 2011 reboot, to clarify, I have not seen the 90's one, but I hear its good too

So much this!

One way I've seen Hunter x Hunter described is "a Seinen in Shounen's clothing". It starts out as one would expect a shounen to, but there are many situations that are quite dark throughout the series, not going to spoil but it's definitely one of my favourite manga/anime out there.