I don't know about Fletcher Moon since I haven't read those books yet (gasp!) but out of the remaining three, I choose Artemis. He's the most unique in personality, as well as having the most unique companions throughout his respective series. Besides, he's the one to whom I can most easily relate, despite not being evil myself. XD
(My avatar was given its awesome existence by the benevolent Voldy.
If Cuddy doesn't look familiar, )