I only have Evernote, but my recommendation is to use both. The basic Evernote account is free, so the only question is do you like Notability enough to buy it.
If I had a reason to buy Notability (I don't do meetings, classes, events, etc); this is how I envision using it.
Use Evernote for compiling those bits of information you may need later, and want to be able to get to from any computer or device.
Use Notability to take detailed notes for classes, meetings, or other events. If you decide later that the note would live better in Evernote, use the email address you will get with Evernote to email the PDF from notability. Don't know how well that will work with audio notes, you can probably mail the audio file, maybe.