Why not both?
edit: wtf are these replies :D
edit2: also to clarify my original comment was meant as both are good. For example you can't easily install MPV on Bazzite and VLC does as good of a job. I do tend to use MPV over VLC but I don't ever crave the other one as I have at least one of those available. I did run into few videos that I had issues running with MPV and vice-versa but those are rare and specific cases. Always the other player did the job so I also can't say that both are perfect.