Gods and Mortals
Runners-up: Year One, LOWW, and the movie.
Year One. I still really like Gods and Mortals, but Year One is more streamlined (like Diana winning the Contest and in the process of leaving to become Wonder Woman, and then Steve crashes, which seems pointless; glad Rucka fixed this) and modern.
LoWW is also enjoyable, wish we had a follow up volume.
Gods and Mortals by far. Year One would've been a close second if not for the lame choice of keeping the daddy Zeus origin and having Phobos/Deimos pose as Ares. Are you kidding me? Diana never even gets to face off against one of her greatest villains?