My favorite characters would have to be a tie between Pam and Kelly. I like how their characters aren't comically funny but just how they are makes them funny characters.
1) Creed 2) Dwight 3) Jim 4) Michael 5) Darryl 6) Pam 7) Nard Dog 8) Kevin 9) Ryan/Stanley (tie) 10) Erin 11) Kelly 12) Oscar 13) Meredith 14) Phyllis 15) Angela