To quote Philip K Dick, I think, "nothing Ubiqs like Ubiquity", and on marketing power alone Apple has blasted most of it's rivals out of the water. Let me be clear the iPod I love is the classic 160gb one that was discontinued a few years ago. I have two, one bought when they were discontinued, and one with a 256gb ssd in it. I'm hoping that will see me OK for a good few years, but the healthy second hand market suggests they will be available, at a price, for some time.
I listen to a lot of Podcasts and Audio books, and iTunes, whatever you think of it supports these very well. There are apps, Audible, Stitcher and so on but iTunes does it all. I have a cable that allows the iPod to talk to my car radio, ubiquity again, and cables, docks, and holders are all easily available, even for discontinued product.
It's made by Apple and the sound isn't as good as some of the HiFi players, although to be fair decent headphones (I use Sennhesier buds) makes it more than acceptable.
I started my proper MP3 player journey with an old Sony 20gb purple egg which sounded great, but the Connect music manager was hopeless. From there I went to a 120gb iPod which lasted years. When that started to fail I looked at some of the HiFi MP3 players and that is where it all went pear shaped. Having been used to the convenience of iTunes dragging and dropping and having artwork files in place was a nuisance. I tried a couple of different players. The Colorfly C3 sounded great but the stupid little screen and impossible user interface made it unusable. Much the same applied to the Fiio X3 except that it just didn't work properly, freezing constantly, and with minimal interest in problems from the "expert" supplier, who thought that great sound excused everything
So back to Apple. Yes they are a triumph of design over sound, but in a world of compromises being able to listen to my music or other stuff without constant frustration and glitches is worth it. Anyway my ears are over 50 years old so how much am I losing? File format makes a lot of difference of course and wherever possible I use ALAC, and buy downloads in 320kbps MP3 or better. In the end it comes down to convenience. Apple has taken over the world because they provide a mix of convenience and quality that works for most people. So perhaps I am wrong about their other products, a couple of clients use iMacs and my daughter won't hear of a phone that isn't Apple. The accessibility and interconnectivity is also persuasive.
Apple are slowly killing off the remaining iPods in their range and look to be phasing out mp3 downloads (as are Amazon) in favour of streaming so we can assume that dedicated music players will start to fade away over the next few years. This will of course drive us all to music, podcasts and the rest on our phones. Where does that leave me? My music life committed to iTunes and my phone world with Android...