I mean, content-wise it's kind of tricky to top Domrona since she's a companion and thus has interactions with a bunch of your other party members, in quests and wandering around various places etc, not to mention several quests that center around her. And of course Kas is the main antagonist so she has tons of content, even if all the repeatable stuff is gated behind her Romantic path. Really hard to compete with those two in sheer volume.
Setting her aside, Evelyn has content involving Cait and Ryn as well as a lot involving the Champ, one scene wandering around Hawkthorne and a backstory that we might one day get to learn more details of, plus Wsan's mentioned plans for future scenes. She's pretty good for content, and IMO the best domme in general. Rina's my second-favorite but her domme content is gated behind two conditions and currently limited to a small number of scenes, though Wsan is working on a big expansion of Brihaus so she should be getting more in the near-ish future.
Evergreen is evil dommy mommy and has a good lot of sex content, but not as much story content yet as there are plans for. so content-wise she's up there. Doesn't really do it for me personally. Orlaith and Mara are both good but don't have a huge amount of content (though I know there are plans for more dryad stuff at some point) and Klemaia's stuff isn't as voluminous but it's really good. The latter three hit all the right notes for me in spite of having less content than the others.
Oh, and might as well mention Arille, who's also a bit light on content right now (and is gated behind Champs with some sort of penis) but has a very good chance of getting more later, both in terms of sex and plot engagement. I'm hoping for the latter at any rate.