What is the best sound editing software for Macintosh?

Logic Pro.

I second @whitecarnations on Logic Pro.

I’d say Logic Pro as well, but it’s not a pure sound editor, more of a audio workstation. If all you’re going to be doing is chopping and exporting it may be a tad much. For that, if it’s really simple, I’d go with Audacity, or Adobe Audition if it’s a bit more complicated.

Oh well… This is going to start a Fan War here but here we go:

The best and only suite of sound production software for professional results is just one: Protools.

Let’s the bashing begins!

Of course, the answer is, It depends. That answer should help me avoid any religious wars, but I do have a preference…

I use Amadeus Pro exclusively for recording and relatively simple clean-up of narration tracks for video as well as casual screwing around with sound. If you are looking for a bargain, there’s even a Lite version for half price.

It’s a tiny fraction of the cost ($59 for Pro, $25 for Lite) of the audio workstations (ProTools: $699, Adobe Audition: $350 or $49/month, Logic Pro: $199, etc), but does most of what I’ve needed for professional and personal use.

Look at the features and pick the one that lets you do what you need to do at a price you’re prepared to pay.

Source: edited audio since the 1970s, video since the 1990s, and was a beta-tester for Avid (parent company of Pro Tools) Media Composer video editor.

PS: There’s a great resource for finding alternatives to specific programs: AlternativeTo.net. Here are alternatives to Amadeus Pro, including some of the programs mentioned above, and some not yet mentioned, but also good, like Audacity, which is a fantastic, totally free multi-platform audio editor.