Just running games is one thing. Having them run optimized is another.

Frankly, you’ll probably not notice a 1 or 2% difference. The main difference is probably that everything gaming related will already be installed, which is nice I suppose, if you’re not comfortable poking around at your stuff. But all in all, most distributions will end up being fairly similar in the end. They all install the same software after all. The only real thing that has changed lately is the immutable ones, should you want to go that way. Apart from that, it really doesn’t matter that much. Find one that works on your machine, isn’t too exotic so you can find other users in case of trouble, and be happy.