Depends on your needs - I prefer Audition as it gives me way much more control over audio (I grew with the program ever since it was called Cool Edit Pro), but I guess if you need to work fast and do simple audio processing, then Soundbooth is ok.
The new version 4 is a great upgrade, btw. Can't wait to get my hands on that.
Richard van den Boogaard
cameraman / editor / video marketing consultant
Audition is a pro radio quality editing and production piece of software. Soundbooth is a tool for sweetening audio and dealing with audio problems connected with video type production. Both can do a great job but you really need to know what you want it for before you can say which is best. For example, some video ppl complained audition was too complex to use - thus Soundbooth was born ...