What is "best"?
Would you mind if it takes a whole day to compress or decompress 500MB? Would you like other people to be able to open the archives even without using Windows or having to download/install some obscure, non-free, possibly malware-infested utility? Would you like to be able to split the archives? Would you like the archives to be "solid" so that to extract a single file, you have to extract every singlefile before it? Would you like the archives to have error-correction information in them? Would you like to password-protect your archives? Would you like the compression algorithm to be proprietary/secret/patented so that when the software maker decides to quit, all your data is inaccessible?
What kind of data are you compressing?