It’s faster (especially to encode), and in my opinion, better tuned for high quality. H.265 can give a “usable” image in a relatively small file size, but it sometimes takes a surprising amount of additional bytes to get rid of the somewhat oversmoothed aspect, and that additional amount can vary a lot from one image to the next, so with the current implementations, you have little choice but to verify visually. At least, that’s my experience with the reference encoder. I haven’t had a chance to experiment with Apple’s implementation.

In contrast, with JPEG XL, I can simply use the high quality setting once per image and be done with it, trusting that I will get a faithful image at a reasonable size.