Not a huge watcher of anime as I was a few years ago but the best that I've seen have been:
Neon Genesis Evangelion - One of the best animes ever created and one of the few that actually was quite deep and made me feel for the characters when something bad happened to them or in the case of Shinji want to smack him one! Both endings created for the series were seriously twisted, especially End of Evangelion, but never detracted from the quality of what came before it.
Martian Succesor Nadesico - Probably my favorite series of all and very tongue-in-cheek, entertaining story and characters although again the ending was a bit of a let down and the movie sequel destroyed what made the series fun to begin with.
Fullmetal Alchemist - The manga is much better but the anime is of a high quality as well, really enjoyed watching this and it only had a few disappointments like the lack of Roy Mustang blowing shit up and the whole story about what the door was was a bit poor. Very well animated throughout and even though the movie didn't end on the note I would have liked it still ended on a nicer note than Evangelion and Nadesico.
Ghost in the Shell: Standalone Complex - Reminds me of American shows like 24 with very high production values mixed with plots where you have to pay attention to. Even episodes where not much happens are interesting to just listen to, the chatroom episode is a good example, although like a lot of anime series I see the ending was poor again. The movies I highly recommend as well although the first is the better by far.
Neon Genesis Evangelion - One of the best animes ever created and one of the few that actually was quite deep and made me feel for the characters when something bad happened to them or in the case of Shinji want to smack him one! Both endings created for the series were seriously twisted, especially End of Evangelion, but never detracted from the quality of what came before it.
Martian Succesor Nadesico - Probably my favorite series of all and very tongue-in-cheek, entertaining story and characters although again the ending was a bit of a let down and the movie sequel destroyed what made the series fun to begin with.
Fullmetal Alchemist - The manga is much better but the anime is of a high quality as well, really enjoyed watching this and it only had a few disappointments like the lack of Roy Mustang blowing shit up and the whole story about what the door was was a bit poor. Very well animated throughout and even though the movie didn't end on the note I would have liked it still ended on a nicer note than Evangelion and Nadesico.
Ghost in the Shell: Standalone Complex - Reminds me of American shows like 24 with very high production values mixed with plots where you have to pay attention to. Even episodes where not much happens are interesting to just listen to, the chatroom episode is a good example, although like a lot of anime series I see the ending was poor again. The movies I highly recommend as well although the first is the better by far.