Due to the time-frame in which I started following anime consistently I consider the anime 'year' to run from fall season to fall season and group series based on when they began. Thus '2008' for me covers shows starting Fall 2007-Fall 2008. Sadly, I felt this period was rather light on ZOMG AWESOME series once 2008 proper came along.

My favorites would be (I don't believe in 'best'):
ef - A Tale of Memories - Shaft being Shafty
Genshiken 2 - Comedy Gold
Minami-ke S1 - Comedy Platinum
Mnemosyne - Dark and edgy action with lots of graphic sex and violence, creepy at times but overall an interesting OVA series.
Druaga - Aegis of Uruk - Action/Adventure/Comedy/GUTS!!!!!
Kamen no Maid Guy - Comedy Diamond/Adamant
Macross Frontier - Singing + Mecha + Klan > (Emo + Whining) * 2 + Whining

Using the ended in 2008 scheme I'd add in
Ga-rei Zero