Erosion control is best accomplished by something that has a deep root system and a wide spreading habit, so any herbaceous groundcover (one that dies back in winter) is not going to work well.

Ferns are an excellent choice. You could also consider Pachysandra or creeping lirope. Their root system is not all that deep but they spread well to form a mat-like surface that will deflect rainwater.

And although I hate to suggest it, in your area, English ivy might even be appropriate.