Rx100
If you’re always shooting in color, and then only see the black and white conversion when you get home, this skill will take a lot longer to develop. You may develop it, if you shoot enough, and are diligent enough, but doing it in camera is going to get you up to speed much faster. If you’re shooting on a camera with EVF, even more quickly. Actually, I think Sony does some of the best black and white creative filters around, and they are accessible to those shooting anything from an A7, Rx100, or the rest of the Alpha line like the A6000.