nowadays I only try to get 8k and avoiding 4k like the plague, 6k or higher although my headset probably doesn't care (quest 3)
It is the most rational thing to do. Not only because the worst 8K video looks better than the best 4K video, but because as technology advances, the lower resolution a video is, the worse it will look in the future. I remember with my first headset, 4K videos seemed to look great because the screen had low resolution. But now with a screen with almost twice the resolution, they look regular, even bad.