Between tar, tar.gz, tar.bz2

For a long time I have been wondering what should be the ideal compression when you copy a bunch of files over a local network. Today I copied a full ubuntu installation of 2 G over the network, piping the tar command into ssh.
Something like:

cd /
tar --one-file-system -cf - . | ssh user@backup " cd /restore && tar xf -"

I measured the time taken with the time command.

And the results:

tar cjvf 19m53
tar czvf 9m20
tar cvf 11m02

So it looks it is the gzip compression which saves the more time.