Personally, it's a mess and I'd love to have a better paradigm.
I have a stack of CD's in my car because I lack an aux-in port, and a cassette deck to put a faux-cassette in. These CD's are burned from itunes, which I now only use to burn cd's because all the music I download automatically goes into my iTunes folder (Even though I have an android now) and I have to physically connect my phone to my computer to transfer files (Not an outright complaint, but it seems like there should be a way around that by now).
All my audiobooks are managed by one app, my podcasts come in through stitcher (Which I'm actively looking to replace, because they just added in-app adds in addition to the ones IN the podcasts themselves, and I make a point to listen to as little advertisement as possible.
So in short, I'm looking for a good way to unify all my audio (mp3's, m4b's, podcasts) through one manager so I can finally get rid of iTunes, stop listening to ads on stitcher and just have a more streamlined audio management system.