I would say if I had to pick one ore, brushed gets my vote for sure, the RM with a bit of polished looks nice, same with the Pams although those are mainly all brushed. Are you thinking of one brand/watch in particular?
Simple. PG is most easily tarnished, so Lange decided to polish all the surface while PT and WG cases have brushed side, which I like better. But, when it comes to Lange, I like all the color Ken