APNG is at best a mixed bag, far from being a significant improvement over GIF.
GIF can have one palette per frame, which can be exploited to improve compression and quality (see https://gif.ski). APNG has to either use a costly true-color mode, which makes it compress worse than GIF, or one palette per entire animation, which gives it worse quality than GIF.
All the GIF-killer formats miss the point. They're trying to beat GIF on being primitive and inefficient, but GIF isn't successful because it's a dumb slow video codec, it's successful because it's old enough to be universally supported.
APNG is a huge disappointment. Its compression is barely any better than GIF, less than 25% in most cases. Inline muted video on loop is easily the superior choice as file sizes are smaller and browser compatibility is better.
The one area APNG would be useful compared to MP4 is where the image itself needs to have a transparent background. MP4 cannot be transparent, it will always be in a rectangular container and a solid background.
I’ve recently started hearing this form of pedantry, but I’m not sure I understand it. “Performant” seems to be defined by the New Oxford American dictionary as “performing well” and claims it is mostly used in computing contexts. What’s the issue with saying “most performant”?
It's vague. How does it "perform well"? Does it mean "faster"? "smaller"? Why not use a word that's not only more specific and well-known, but faster to read and pronounce?
FWIW, to me performant has connotations of conformant, so performant implies "performing to spec". I also think it implies in general doing what it's supposed to. Maybe that impression is incorrect but it is my impression.