While I tend to avoid encoding wherever possible, I use H265 10Bit at low RF to archive non-critical libraries (old TV shows in some users personal libraries, 1080p movies more than 1 year old and over 20gb etc…).
my average size reduction going from a 1080p Bluray remux of 35-40gb is about 50% with no significant effect to image quality. High action or high grain movies end up a bit larger, slower movies with no action and most animations compress a bit smaller. works well overall.
basically any modern device can decode them and the image quality tends to be a bit better than 8bit.
I’d like to go with AV1, but very few of my client devices can decode it, so its not worth the trouble to save a few percent,