A:Answer For league, I know for certain it looks pretty nice. I don't know if it actually widens the amount of the field you can see, but it sure gives the impression that it does. Seems more tactical to me.
I know Battlegrounds and Fortnite do well with ultra-wide gameplay, and as games similar to h1z1, it should be fine. One thing to watch out for are lazy developers though. Some games require a few extra steps in order to get them working at 21:9 resolutions. And some game simply don't work at them. Get well acquainted to googling 21:9 support (insert game name here) for some older games.