Cross breeding is pointless if it isn't improving anything especially in a breed like AC where the standard is still all over the place.
The AC need more folks working to breed high quality Cemani and getting them to nice standard.. so you can tell when you are looking at a Cemani.
Your other crosses.. if it's decent Cemani the melanin thing is dominant and you end up with all black birds anyways.. just NO actual value.. NOT discounting your personal fun and enjoyment though.. you MUST do what YOU love or it's work. This is just MY opinion! Since you asked.
IF I was going to cross Cemani to something.. it *might* be like a white Leghorn.. to improve laying ability while maintaining body/comb type, and even test the Fibro gene for purity..
Sounds like you have a lovely collection in your flock. Happy adventures!