A very interesting comparison among different compression software.
The global score of each software is calculated on the base of the
Compression Ratio, the Compression Time and Efficiency Ratio.
Lossless data compression software benchmarks / comparisons
At the moment the best compression algorithm is PAQ8H (on October 27, 2006, it was announced that the PAQ8HP5 variant won a Hutter Prize for Lossless Compression of Human Knowledge of 3,416 euro), but I think I will continue to use WinRAR