Garageband is the dedicated audio editor included in Apple computers. It is highly capable.
Logic Pro is the professional Apple app for audio editing. I have it and it is great for editing short passages, perfecting them, and stitching them together to make a full track.
I would describe Garageband as the tool to use if your track can use a strict metronome marking. Use Logic Pro if you need Rubato (or flexible timing). Many other diferences exit, but that is one of the most basic.
There are also Mac versions of tools like ProTools, which are competitors to Logic Pro.
iMovie has some pretty good audio editing capability as well, if you are editing video, but I would not use it to edit audio only.
GarageBand should have come free with your Mac.
If all you need to do is remove noise or hum, iMovie, Logic Pro, and GarageBand can all do that as well. But there are free tools like Audacity that can do this. http://audacity.sourceforge.net
I didn't know about Logic Pro but if it uses the same approach as Garage Band I doubt it will help my quest. I am quite familiar with and have used all the other applications you mentioned. Of those I use Audacity the most as it's designers seem to grasp most of the features that a professional editor requires, except scrubbing.
I guess the editing power and precision of scrubbing will never be truly understood by newer generation audio editors until you have actually had the hands-on experience - each hand holding the un-braked reel hub of 10.5 inch reels of low noise, half-inch, two tracks stereo classical music or voice, with the client's specification of removing a very quiet, very indistinct tiny sound, almost lost in the noise floor of the music, almost.
In "reel" scrubbing the speed and volume of the passage are under infinite control of the editor. It brings editing to the level of being an art, not just a slice and dice job.
Garage Band must be some sort of "training wheels" approach to audio editing, maybe belonging to the Toys R Us catalog. Garage Band has the reverb switch turned to the "on" position when recording any track. Did the concept of record "dry" and add reverb and other "wet" effects later, after the mixdown or maybe in post production get completely lost in a generation of audio editors?
There might be a Pro Tools product that could meet the quality standards I need but I'm not sure. Pro Tools seems to be hardware purveyor,focused on the multitrack, overdubbing crowd, not the location recordist/editor who rarely needs more than 4 in, 2 out. But thanks for the response.