I use Unarchiver as well. It simply works without having to configure a lot of stuff, and it's noticeably faster than Windows apps like WinRAR that do the exact same thing.
I have three that I use--two mentioned here--unarchiver and MacPAR Deluxe (which can do additional things--especially handy if you like Usenet). One of the best still works in Mavericks although it is no longer supported--and it is still available to download--SimplyRAR.