I'm slightly surprised that speed and file size would be the only considerations. For an archival format wouldn't you at least want a format with very robust e

I'm slightly surprised that speed and file size would be the only considerations. For an archival format wouldn't you at least want a format with very robust error detection, even error correction? None of the proposed formats have this, basically just having a simple 4 byte CRC or XXHASH. Some kind of random access to the compressed file might be useful too (which xz has).