I think that the coloured versions are likely to be easier to see, depending on what your background art is going to be. With greyscale it can easily become a bit muddy and the shapes become harder to tell apart if you don't work with harsher contrasts or outlines.
I don’t have a clear preference between color and b&w, depends on the rest of the game, what mood you’re going for, I guess. I just wanted to suggest using a different title for this thread because the current one "Help Me Decide !!!" does not say anything about the actual topic. Also the three exclamation marks are somewhat aggressive.