As a major compression-freak, I test all new released compression-programs out there. I stick to my main WinRAR though. Ofcourse, 7zip is free en compresses slightly better, but misses a lot of features that WinRAR does have. What about extracing multiple archives in a queue modus (reduces your CPU load), deletes archive-file(s) after extraction, deletes added files after creation of a new archive, multi CPU, etcetera. It worth's its price, but only if you don't want a nagscreen.