I think #1 reason for me is AoD has choices that matter. Part this is obviously that dialogue options frequently lead to different consequence, whether big or small. (What's the point of having dialogue options if they all down the same path?)… But I also mean the choices you make in terms of how you build your character matter. A lot. In AoD skill checks are hard checks where there's no random (i.e., dice roll) element. You try to sneak by a guard and in that case you need at least a 5 sneaking skill or the guard spots you. I'm not saying that adding a random component would necessarily be bad, but "too much" randomness leads to how you built your character not mattering as much as dumb luck… So I think having hard skill checks is a nice way to ensure that how you build your character matters (it is still unpredictable because you don't know exactly how many points you need to put in a skill for a given check unless you either look it up or reload / experiment). As such, the game has a great deal of replay value.
In general the writing is very good… Setting is a good mix of the familiar and something different. The characters are pretty realistic; how you'd expect most people to act in a world that seems hopelessly doomed. Many RPG with moral decisions make them black and white; possibly even having a meter. The game doesn't judge you, characters react as you'd expect them to… Sometimes bad behavior is rewarded, sometimes being kind is punished, 'cause life isn't always fair. Many world events will happen outside your control but your choices still have an impact.
Lastly, I think AoD has a solid turn-based tactical combat system (even though combat not really being the main focus of the game) and with certain backgrounds / builds you might avoid it entirely. You have options that can affect the outcome. There's random element, but again how you build your character matters a lot. There are a few powerful items in the game that can make a huge difference, but for the most part your character's stats matter; you cannot endlessly grind exp or loot to the point where your character is invincible… It's fun and it feels like every combat encounter serves a purpose. You're not just fighting endless generic enemies because this isn't that kind of game.
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