WebP lossy and WebP lossless often get mixed up. They are substantially different. While the former is mostly just outdated VP8 4:2:0, it is fast and more pleasing to the eye than JPEG at low quality and more practical there, given it has transparency. The latter is a pretty good option for ARGB images offering 25% improvement over PNG [1], and 20-40% on top of that with near-lossless compression.

[1] https://developers.google.com/speed/webp/docs/webp_lossless_...