Re: Quality, not features
I'll see your Podcasts point and raise you one intensely irritating problem with the Music app. (Podcasts wasn't too bad in iOS 10, but when they made it more "Music App like" in iOS 11 the hell really started)
When iOS is short of RAM it boots apps out of working memory - they're supposed to shut down gracefully such that they pick up in the same state when reopened (where this makes sense). The Podcasts app can be force killed and still reopen on the same podcast at exactly the same point. Ideal - exactly as it should be.
If the Music app gets closed for any reason (force close or RAM shortage) it forgets everything - playlist, track, position. "Not that big of a deal", you're thinking? I listen to radio shows that are usually 2-3 hours long so I have to remember where I left off as this happens on a semi-regular basis even though my 6S has 2GB of RAM. This has existed since I went iPhone in 2013 and despite reporting this I've been similarly ignored. If they can do it in the podcasts app they can surely make it work in the music app!
Then there is the "Delete a track in iTunes, then sync and get a duplicate version of the playlist in iTunes and on iPhone" bug which has persisted for about two years now (since about iTunes 11.2?)