You're asking 2 different things.
1. a 'gaming' SSD. There is no specific SSD that is better or worse for performance in games. Samsung 850 EVO. Go with that. Or the Crucial MX100. Either will work.
2. SATA Express on your motherboard. AFAIK, there are no specific SATA Express drives out yet.
Again, the Samsung 850 EVO, in a regular SATA III port, is what you want.