AVIF has progressive support in the spec, but it has not yet been implemented in an encoder and it is very likely going to be less dense than the non-progressiv

AVIF has progressive support in the spec, but it has not yet been implemented in an encoder and it is very likely going to be less dense than the non-progressive coding. My guesswork is that it will be ~10 % less dense than non-progressive once implemented, but it is just a guess with my pass experiences of other codec experiments trying to do such things. Otherwise both formats have all features. JPEG XL is yuv444 by default whereas AVIF tends to favor yuv420 and some encoding/decoding hardware is going to be yuv420 only, so with AVIF one would often need to go software coding to get yuv444 quality.