I don't hate domain play, but it's not my focus by a long shot. And let's not kid ourselves ACKS's forte is in domain play. Its AC system is... decidedly wonky. I've gotten used to it, but it took some doing. I don't care at all about realistic simulation-- for god's sake my second favorite edition of D&D is 4e (and 3.5 remains my least favorite)!
So what is it? What draws me to ACKS?
Is it the little tweaks? Things like the system of cleaving present in it, or the mage's repertoire and magical research stuff, the hijinks, the d20-based thief skills, or the list of poisons in the GM chapter? Is it Domains of War (which I've only got the free version
of), which makes for a fun, effective battle minigame with more for tactics
than the BECMI War Machine?
Is it the proficiencies system, which does one of the best jobs of scratching the itch for feats and skills that my WOTC days imbued in me?
That's definitely a factor.
But I think I know what the number one reason is.
It's the classes. I'm absolutely a class slut. The more the merrier, in my book. And ACKS, between itself and the Player's companion, contains pretty much all my favorites. It has my favorite OSR ranger, my favorite bard anywhere, and a solid assassin, and that's just in the core book. The only one missing is the Warlord, and between the proficiencies available to the fighter and Thomas Weigel's excellent Aristocrat class, I'm more than taken care of. And should the mood strike me for a class that isn't already around, the Player's Companion explained the Autarchs' math well enough that it's the work of half an hour to bring my new class into the world. Ultimately that's the biggest factor in my choice.