tl;dr: Bzip3 is a modern successor to Bzip2 that combines a Burrows-Wheeler transform (via suffix arrays), LZP preprocessing, and an order-0 context mixing entropy coder to achieve significantly better compression ratios and speed. In benchmarks compressing a tar of all Perl5 releases, bzip3 outperformed xz, bzip2, and zstd on ratio (546MB vs. 2GB for xz), with decompression time competitive with zstd. It's LGPLv3-licensed and works well for text and code, though the author warns of the usual risks of relying on a newer compressor for irreplaceable data.