[JyrkiAlakuijala]

Brotli decompresses 3-5x faster than LZMA2 and is within 0.6 % of the compression density, and much better for short documents.

ZStandard decompresses ~2x faster than Brotli but is 5 % less dense in compression density, and even less dense for short documents or documents where the static dictionary can be used.

Brotli is not slow to decompress -- generally a little faster then deflate through zlib.

Last time I measured, Brotli had ~2x smaller binary size than zstd (dec+enc).

[GuB-42]

Straight from the horse's mouth!

The thing is that Brotli is clearly optimized for the web (it even has a built-in dictionary), and ZStandard is more generic, being used for tar archives and the likes, I wonder how PDF would fit in here.