I used to use Color Finesse 3 for virtually all my edits in FCP 7. And missed it greatly once I moved to FCP X. Of course, it was never bug-free as a FCP plug-in.
I passed on Nattress Curves, as it’s really NOT a curves plug-in. More of a highlight, mid, shadows adjustment. I also find the “Curves” section of Colorista not flexible enough.
I think the closest you’ll get right now is Color Finale. It is quite good, if a little bit buggy at the moment. It doesn’t have color pickers, which would be nice. I combine it with Dashwood’s White Balance plug-in for FXFactory which I find is the best at correcting white balance with Kelvin adjustments.