I couldn't be happier with my CS FS-PRO, I had BR for years and one thing that annoyed me with the BR system is the fastener being at the tripod mount of the Batt. grip/ camera. I hated it when shooting vertically and if I wanted to use a tripod, I have to unscrew the fastener.
With CS FS Pro, you can shoot horizontally and vertically without a problem. With the F1 plate, you can mount it on an arca swiss compatible ball head otherwise, you can still mount your non arca plate on the F1. If you're using an RRS L bracket, BR would be the choice as you have the option to purchase the RRS clamp - the only downside is that you need to purchase additional accessories to really secure your gear as the RRS clamp has the tendency to slide.
If you're talking about camera Sling Straps, BR & CS are on top of the list - being an owner of both - I'll go with CS.