For erosion ground cover fora hill and slope good drop off. 3 favorites easy no maintains care in zone 6
These articles should help:
https://www.gardeningknowhow.com/special/slope-hill/hill-ground-cover.htm
https://www.gardeningknowhow.com/special/slope-hill/plants-that-grow-on-slopes.htm
https://www.gardeningknowhow.com/ornamental/foliage/ajuga/ajuga-bugleweed.htm
https://www.gardeningknowhow.com/plant-problems/environmental/plants-for-erosion-control.htm