As I've written elsewhere, I think both are overpriced nora-wise right now (having to do with the 3-5 range while passive on RC and limitations on rite of creation). That said, it depends on the role you need in your bg, but I think you'll find ritual cultist to be a bit more useful. If your opponent doesn't have magic damage out, she can contest a font for a long time. She can be used to bypass defense (magic bomb) or to combat healing heavy factions (disease bomb). She heals and her extra AP can be used to fuel AP heavy-equips like slaver's whip. Even though I'm experimenting with RC, I'll probably remove her from my meta bg soon because there are probably better options (I just really like the sprite!).
In meta I tend to run Ritual Cultist more, but depending on what else you are running kanen cultist synergies well with some SP setups. Designate Scapegoat can win games.
