American Crime is potentially one of the most engaging, powerful shows to come along in years, but with that potential comes the possibility that it will ultimately all come crashing down. It's riddled with complexity, by design, and because it doesn't have forever to work its characters, they are drawn with broad strokes, meant to represent "America" in a grand sense that may make it hard to hook audiences.
Outlander delivers better than even those with high expectations had any right to expect. That's not because the books aren't good (I don't know), but because the translation to screen has so many mistakes to avoid. You can see the series avoiding them, and that's a kind of magic itself. It's fun, but has just the right amount of depth to keep you hooked.
Call the Midwife has a hurdle to get over with the fourth season, and it hopes to manage it with new introductions.