I will assume that the average effective broadband connection is about 20 MB/s, and both xz and zstd decompressions are faster than the download under this assu

I will assume that the average effective broadband connection is about 20 MB/s, and both xz and zstd decompressions are faster than the download under this assumption. But there are lesser known compression algorithms that are more efficient in terms of compression ratio for this target decompression speed, like zpaq [1], which are rarely considered as alternatives. So multiple factors exist here and I believe zstd excels at pretty much every other factor compared to xz, making it a very likely choice. [1] https://mattmahoney.net/dc/zpaq.html https://mattmahoney.net/dc/zpaq.html