Check out the search for BR vs GS, you'll get plenty of hits. Anyway, here's my standard response:
BR are the more representative and better overall tests. GS offers a great value, but is weak in verbal. If I had to pick which ones regardless of cost, I'd get the 7 FLs from BR. Spending the money on the better FLs could help avoid the cost of retaking again by better preparing you for game day. Lastly, if you haven't taken the AAMC FLs, get those first.
Another thing to keep in mind is that recent test takers haven't liked GS tests. However, there isn't much feedback from recent test takers on BR tests. What little feedback there is, usually is positive. So, let me reiterate that you should pick up the AAMC FLs first.