Wicked Rogue.
The mechanics aren't that different from Bifrost, though Wicked Rogue has interesting combat and feels more akin to a standard F95Zone style VN, though unlike a lot of VNs Wicked Rogue has an actual game at it's heart. The combat is interesting and you need to succeed with that as well as with running your brothel.
I played Wicked Rogue first.
I wish Wicked Rogue was a little more difficult, but I also felt that way about Bifrost.