I have no problem with iTunes and the stock Music iOS app, and I have yet to hear about an alternative that lets me keep a list of smart playlists in sync between the two.
I use Ecoute. Started several years ago because I didn't like the Music app interface. It's simpler and cleaner and will use playlists created in iTunes or Music app. There may be better as I'm not one to shop around once I find something I like. As always YMMV.
I have no problem with iTunes and the stock Music iOS app, and I have yet to hear about an alternative that lets me keep a list of smart playlists in sync between the two.
The various forms of Google Music, including the actual Google Music app allowed this.
At one time you could use Google Play to sync your iTunes library to Google - including playlists. Any change you made in the library reflected to Google and down to the apps.
Now it's YouTube Music and Google Play long ago stopped supporting PowerPC Mac and the plugin that allowed the library syncing.
I use Soor. The main reason is because you can sort playlists by last date added order. Its a very slick app too other than for that reason and seems to be updated with new features almost weekly.