Get the Shimano BB. FSA puts out so many different types of BBs- that are all just a bit different - that's it's a pain in the ass. A Shimano Hollowtech II BB is a Shimano Hollowtech II BB. You can mix and match any level of crankset with any level of BB as long as they're both Hollowtech II.

The Shimano crankset will shift better than the FSA one, too.

IMO it's a no-brainer.