I second popos and mint. I love fedora but if he is a gamer you want something that will just work (navida built in or a very easy one click mechanism to get it). If he has to research PPAs and installing rpmfussion it will get all too hard very quickly. Also do some expectation setting before hand, research what games he plays work on linux, better he finds out now rather than after 2 hours of pain or getting band for “hacking” because of proton triggered an anti-cheat thing.

Edit: I run fedora on all my machines except my gaming rig which is popos. Fedora works too but popos is hassle a free experience.