Usually each program will do something slight better than another program. Vegas will let you mute breathing noises as well. Cool edit will "locate" the sounds for you and allow you to create a "profile" of the sound, store it and use it as an automatic search and find in later recording/tracking sessions.
Really what you need to know is which program you want to use the most. Also, consider how many programs you want to "run" when you are recording and mixxing. I, for one, like simplicity. So anything I can do inside Vegas (my fav. software) regarding mixing, editing, etc. i will usually opt for doing it in Vegas - even if a seperate program might get a smidgen better . . . but if the difference is too greatlly noticeable - I will opt for an "out-of-Vegas" program . . .