If you want the highest quality for normal users, you would go with PNG or SVG.
While if you want the highest savings on space, you would go with something like JPEG or WebP basically.
What I am talking about is how challenging it is to upload PNG or SVG files without conversion.
I support Fediverse admins choosing to convert all the images and videos to a compressed formats for sure. But I always look for the best quality if available.
Arcade Rage.