Best Buy's blog has the details on the two pre-order exclusives:
Gears of War 4: Pre-order it and get the Elite Gear pack, which contains the Vintage Del character, the Black Walnut Gnasher weapon and three bounty cards. Oh, and you'll also get a Gears of War mug and coaster set. It's a complete win.
Forza Horizon 3: Pre-order the game at Best Buy and get the 2016 Jaguar F-TYPE Project 7. Not only that, but you get a controller stand and skin. So you can play (ehem, drive) in style.
Best Buy's Gamers Club Unlocked has a two-year membership for $30. Members save 20% off new game purchases, plus 10% off pre-owned games, among other benefits: