I didn't intend to create another opportunity for jpeg-xl partisanship, but well, it happened.
> Yes. One can barely argue AVIF is better than JPEG XL on the Web.
One can very persuasively argue that AVIF is better on the web; for 99,999% cases used in the wild it will be better. Yes, some marginal cases are better handled by another formats, it is nothing unheard of.
> For authoring, JPEG XL win hands down.
For authoring, .psd, .afphoto or whatever is the native format of the used app will be used.
That said, unfortunately AVIF is not a substitute for JPEG XL...
1. AVIF has an order of magnitude slower saving / encoding speed vs JPEG XL.
2. AVIF in "lossless" mode tends to be bigger than PNG- and it isn't truly lossless, just best effort (based on the AV1 video format).
3. JPEG XL supports orders of magnitude higher resolution, bit depth, and is an actual replacement for lossless PNG.