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I always have Stuffit Expander and The Unarchiver to sort my unarchiving needs :)
 
Stuffit Expander is a piece of ****. The Unarchiver is decent but sometimes chokes on certain multi-part rar sets.

I'd highly recommend UnrarX if you just need unrar support, or MacPar Deluxe if you need par2+rar.
 
unrarx for password-protected rar

though lately I've been using BetterZip
 
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