If you want all black offspring, no matter what you want to go with PBL. Also they are said to have thicker shells and brighter colors as they are pure. They should produce nothing but identical copies, you can always cull them for particular patterns, shell thickness, etc.
If you go with CBS of any kind, they could potentially throw reds and goldens.
I literally just got a batch of PBL today and i am truly blown away right out of the box, so i cant wait til they get comfy and to maturity. I like the blacks as well and didnt want to have to worry about trying to catch other colors in a planted tank.