500GB 850 EVO is the best pick. You don't need an nvme ssd for a gaming rig. While those ssds have far more potential performance, they need really intensive workloads to actually push them hard enough to enable them to pull away for the (already plenty fast) mainstream SSDs like the EVO. It's like buying a top end sports car to drive around New York City. Sure if you're on a race track those cars are way faster, but if they're always waiting on traffic lights or other cars, they're never able to go any faster.
Get an EVO either in a larger size (allows you to put more games in it), or pocket your money or put it into more important components, GPU, CPU, etc.