Well, for one thing I like its adaptability. Rather than being confined to a single genre or style, we could realistically play any setting we want; we could be an Achaemenid satrap and one of her cataphracts, a mamluk serving her Ottoman empress, Frankish knight and duke, really whatever we wanna do. Of course it could even be strictly fantasy, like a half-Victorian-half-medieval, gothpunk, old-school Castlevania type of deal.
I also like power dynamics in a pairing, as well as the obvious and multi-faceted sources of conflict, from arranged marriages to court intrigue to war.
And finally, I appreciate that you're not looking for smut, and that romance is strictly optional for you; something to be eased into if there's character chemistry, rather than coerced from the circumstance.