what is more popular silver or black face plates

I don't really care, I guess......never really thought about it too much.

Black is beautiful!

Silver, since day one, in the '70's.

I prefere black, as silver is a visual distraction from the music being played.  

Definitely agree with @jwei's recall that it is cyclical. In the UK, I would say that at the moment 'premium' comes in silver; 20 years ago, it was black (and 20 years earlier, it was again silver).

Personally, don't care. I have a mixture, depending on what I find/is available/cheaper.