I'm a big supporter of JPEG-XL. It has something very unique that has not been seen in an image file format before: An option for Lossy compression that isn't DCT-based. So you can't get ringing or blocking, because there are is no DCT at all. The actual artifacts you do get are not at all like what you get with JPEG. Instead, you are likely to see things like slight pixellation or banding when your quality level is too low.

In order to get the non-DCT lossy compression, you need to request "Modular Mode" in the program that compresses the image. But for some reason I don't know, Irfanview is literally hiding that checkbox from you, and you can enable the feature by editing the dialog resource and making the checkbox no longer hidden.

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Meanwhile, I still prefer WEBP for lossless compression, because the decompression code is so fast. In terms of who has the best lossless compression, WEBP and JXL easily beat AVIF, and JXL usually beats WEBP, but not always. In one case, I saw a grayscale BMP file getting better compression with FLAC (!) than JXL.

WEBP's lossy format is just not that good, AVIF and JXL beat the hell out of it, sometimes the JPEG even looks better. But WEBP's lossless format is excellent.