Another vote for the Black Patent. The silver one is very rock-chic and looks like a bag to be carried out at night and not so much for work?
As for the bag being patent, I think it would add a little zing to your outfit. I know what you mean about making too loud of a statement with your work clothes, but remember it depends on what you are wearing! A little patent is like a little bit of pretty bauble - it only enhances the current outfit. What I like about the patent is that you can look casual-chic with a pair of jeans and tshirt too.