I'm indeed interested in the author's opinion about the zstandard format. Because one seems to use xz as a kind of scapegoat...

And if for some reason zstd is not acceptable, the LZ4 format is still not too bad. Same author as zstd, relatively well supported, and the format seems even simpler to implement compared to Lzip.

So if for some reason I can't use Zstd, I would still probably choose LZ4 instead of Lzip.