I think B looks the nicest of the three by far. Good use of a monochromatic color scheme, nice balance between background and foreground elements, perfectly readable at a distance.
The design direction of A is a bit busy and stands out a little too much IMO, it looks kind of out of place next to stock iOS apps. C looks a bit too amateur, and has several tangents in it that really bother me - I do like the overall idea of it, but it could really use a rework.
I started with C, but then clicked the links to compare what hey all looked like on a Home Screen (yes, I eventually followed instructions .. look at me go). B is clearly the standout for me.