GarageBand is great for demo tracking for songwriting and and simple audio editing of spoken word or podcast applications. It is also great for making EQ adjustments on audio from other macOS or iOS programs for easy export back into those programs. GarageBand isn't well-suited for mastering, however, and it's a little difficult to get volume levels up in post-production if capture wasn't just right
WaveLab is well-suited when you want to apply a lot of VST FX processing to audio, or do a real-time recording and be able to hear how the FX processing sounds as you're recording. It is an excellent tool for recording in the studio. However, it lacks the sophisticated multitrack capabilities you find in a Digital Audio Workstation (DAW), instead of focusing on the features of an audio editor. It is also great for quickly opening, editing, and saving a lot of files because of how fast it is.
Realtime FX Chain - This is the big one for me. I always had both WaveLab and Sound Forge (along with some other audio editing programs, and using Pro Tools at school). Of the two, I preferred Sound Forge for its user interface and hotkeys, but I preferred WaveLab for its realtime FX. The ability to easily chain FX together and tweak them on the fly while the audio is playing is enormous for me.
Speed - Quite simply, saving a huge file in WaveLab is orders of magnitude faster than in Sound Forge. To this day, I don't know why that is, but it's just faster. Opening and saving files is a breeze in WaveLab, while in some other audio editing programs, it can take 30 seconds or a minute for a large file.
User Interface and Hotkeys - I've always struggled with the UI in WaveLab, and even after all these years, I am just much faster in Sound Forge. I used to have a job as an audio editor, where I edited hundreds of hours of interviews. By using the "Mark" feature, I could easily cut out silence, "ums" and "ahs," and other audio artifacts in Sound Forge. I struggled to do the same in WaveLab but was never able to work even a fraction as quickly.
Built-In Audio Processing - I much prefer Sound Forge's built-in audio tools like time-stretching, normalization, compression, and so on. WaveLab has many of the same tools, but I have not found them to be as easy to use, and in some cases, nonexistent (relying instead on a VST plugin).
It's dang simple for anybody who knows even a little about recording software. It's not something just anyone can open and immediately be a professional at, but things are clearly marked, the help documentation is great, and it's easy to explore and discover functionality that can aid in your production workflow.
I have never contacted Steinberg, so I am not sure how responsive they are. Still, I've watched countless tutorials on audio editing and mastering in WaveLab, so I am pleased with the level of support available from the online community of users. It is a much-loved program among audio industry professionals, and there are all sorts of great tutorials, tips, and tricks available online.
Adobe Audition is another great audio editing/recording software, in fact it is much better compared to GarageBand and has much more effects. However, it has a pretty large price tag while GarageBand is completely free. Also, Adobe Audition has a very steep learning curve which makes it hard for our staff to get used to the software. Considering all this and after deep analysis we decided to opt for GarageBand, well at least for now. We may change in the future depending on our needs.
I am relatively agnostic about what audio software I use. I still use WaveLab to this day, 21 years later, for applications where I want to apply effects chains and tweak them in real-time. Sound Forge even can't do this for some reason. But when I have a lot of editing to do, I'll typically open Sound Forge instead, because I prefer the workflow of using the "M" hotkey to mark the audio as it's playing, and then quickly skip through markers and edit out audio artifacts. When I'm recording a vocalist, however, if I am not using a Digital Audio Workstation (like Ableton Live), then I do prefer WaveLab. I can apply VST effects in real-time to the audio coming in through the sound card input and playing back in their headphones.