The consensus here seems to always be leave in SDR and use match content, but I’ve had no issues with leaving Dolby Vision on all the time. SDR content like youtube and TV shows that were never mastered in HDR look 100% fine to me. Part of the Dolby Vision spec is that it forces your TV into it’s most color accurate settings so why wouldn’t I want that as well? Using an LG C2 by the way.
What I’ve learned from many many YouTube videos is that you should select 4k SDR as your main video format and then enable match range options. This is because you don’t need Dolby vision or HDR even for the apple tv menu elements. You’ll only want those when you’re watching something — and it’ll automatically switch your mode to the best possible format provided by the show or movie. So if it’s available on Dolby vision it will show you it in dolby vision and then switch back down when your browsing and so on and so forth.