If I will need to access individual files or it needs to be usable by others on arbitrary operating systems, zip is best. Random access is greatly helped by th

If I will need to access individual files or it needs to be usable by others on arbitrary operating systems, zip is best. Random access is greatly helped by the directory at the end of a zip file. .tar.*z is particularly hostile to random access. If I just need an archive for easy schlepping around, I use tar if the content is not likely compressible or tar.gz if it is compressible. The slowness of better compression or the likelihood that I will struggle with missing utilities tends to make me shy away from other compressors. I would only highly optimize for size and suffer the slow compression if it will be downloaded a lot of times and that makes a difference for user experience or bandwidth costs.