Ask jpegxl.info, AVIF performs better in some ultra-low-filesize/bitrate scenarions but JPEGXL is better in most other areas and supports progressive loading which is useful for internet purposes. Plus you can losslessly transcode old JPEGs.

Personally I want to use lossy compression when I want to avoid a 35mb PNG, and AVIF just did not do as well as JXL with bringing the various massive PNGs down to size.

ⓘ Remember to enable JPEG-XL support in your browser, even on your phone!