I adored season 3. I thought it was just so much awesome. I love how each season Dexter becomes a little more human, and I loved/hated that he thought he had a friend. I also loved Rita/Dexter and the proposal scene. And there was a fairly happy ending to the season, as well, which was cool.

S2 was always my favorite, but I pretty much love all three seasons equally. Dexter is probably my favorite show of all time (yes, even above Doctor Who) and I cannot wait for September '09.