USB Wi-fi Adapter

So im trying to help out my friend with him getting a pc. He has no access to ethernet due to his wifi router being on the opposite floor of his room and he doesn't want to drill holes and stuff through the wall to get ethernet. So i am wondering what is a Really Good Wireless Internet Adapter that is gonna be good for gaming and wont cut out or in that often. Im asking because ive had bad experience with wifi adapters before on my old pc build. Note that the Computer he is using is just a practical upgraded Dell Optiplex 9020 with no M.2 Support that I know of. (mini tower optiplex)