Recently some of my older publications were accepted and naturally were archived on the Materials Archive. That being said, local copies are also nice to have. The best compression I know of is basically via the Lzma RZIP :

1lrzdir=gprd_sella_bench; \
2    tar cvf $lrzdir.tar $lrzdir; \
3    lrzip -Uvvp `nproc` \
4    -S .lrz -L 9 $lrzdir.tar; \
5    rm -fv $lrzdir.tar; unset lrzdir

Which should be decompressed with:

1lrunzip -o - gprd_sella_bench.tar.bzip2-lrz | tar xvf -

Though I do hear good things about 7z too.