7z and RAR are both a compressed archive file format. RAR is a proprietary archive file format and 7z is available as open source. 7z main features are; open (alows any compression or encryption method), high compression ratio with LZMA, strong encryption, large file supports (up to 16 exabytes) an unicode file name. RAR main features are; high compression ratio, strong encryption and recovery record to recover damages archive. Usually the files on the internet are archived using ZIP and RAR, and I seldomly see files archived using the 7z format.

Which have the better compression ratio, RAR or 7z?