This is a highly subjective question and with as many more questions as there are answers.
What is your budget?
What type of material do you listen to? CDs? MP3s?
Do you really want stereo (2 channel) or do you want Home Theatre (5.1 or 7.1 or more)?
Asking for 'the best sound' is like asking for 'the best car' or 'the best computer'.
First you have to know what it is you want to use it for. Secondly, you have to go into the store and listen for yourself as you are the ultimate judge.
Of course the more expensive systems will have more features, but whether or not you can hear the difference is up to you.
