The best free to play games for the Nintendo Switch are:
-Call of Duty Warzone
-Fall Gayys (Playstation Plus)
-Star Trek Online
-Mobile Suit Gundam
and the list literally goes on…
You realize that google search engine could quite easily answer your question much quicker than me answering this for you directly right?
In terms of the best ones that I’ve had the most fun with it would be Fortnite and Warzone, and mildly Apex Legemds. Rocket league is cool to but it’s simply not for me. Rogue Company isn’t too bad either but I’m not a fan of the 3rd person perspective.