1) Chuck. - Something about this show just makes me love it. And the ending, oh man :'(
2) Community. - This may be the funniest show I've ever seen. And there's such a diverse range of topics covered, but in a light-hearted, parody manner (zombies, paintball, animation, 8-bit video games).
3) The Mentalist. - This show is amazing, so much emotion, and the acting, particularly Simon Baker's, is phenomenal.
4) Breaking Bad. - Sooooo good. Hard to predict, emotional, amazing acting by the entire cast.
5) Dexter. - Haven't fully caught up on this show, I'm only into season 4, but from what I've seen, this show is really good too.