Isn't bzip used quite a bit, especially for tar files?
[0]: https://meta.wikimedia.org/wiki/Data_dump_torrents#English_W...
“Best” is measured along a lot more axis than just performance. And you don’t always get to choose what format you use. It may be dictated to you by some 3rd party you can’t influence.
- better compression ratio than gzip
- faster compression than many better-than-gzip competitors
- lower CPU/RAM usage for the same compression ratio/time
This is a niche, but it does crop up sometimes. The downside to bzip2 is that it is slow to decompress, but for write-heavy workloads, that doesn't matter too much.