Have you tried Google's jpegli encoder? I find that it generally matches webp for most image types. Quantized png is usually best for anything with a limited color palette though.

WEBP/JXL is best for lossless, AVIF is best for lossy. But WEBP is more widely adopted (and also decompresses faster than JXL).

Webp is much better for lossless.

I have a similar tool at https://pictolab.io. I use it for tweaking the brightness and satuation of images mostly. For that you want HDR to reduce clipping, and most image formats have surprisingly bad HDR support besides AVIF (and jxl). Jpeg kinda supports it with gain maps but it's kind of tacked-on to the spec. Webp doesn't support HDR at all.

It's also surprisingly hard to support HDR input. For example, Apple uses a weird poorly documented format for the HEIC their iPhones take. I feel like HDR is just kind of a mess right now.

Lol I went through that same webp-vs-avif thing. AVIF supports HDR, so that's a good reason to switch.

> for screenshots though, and WebP works better for those

Interesting! Better in terms of more quality preserved or smaller file size? Have you found other types of images where this applies?