Hmmm, I would start with either Talisman or King of Cats. Or perhaps Mystery Date. From what I know of your SF reading preferences, this really is exactly your kind of series. You might well like Sin Eater if you give it another try, though you may need to get invested in the series first. It is a bit rough in patches, as she tries to stuff a lot in there, and yet still leaves a lot of (to me fascinating) lacunae.