Ask HN: It's 2018, best way to manage files on Apple devices?

I just spent the last hour trying to sync an mp3 audiobook to my iphone from my work computer and ended up deleting everything that was on it via iTunes syncing progress. Apple seems to make it harder and harder to manage my own files on my iDevice with each release, and worse than doing nothing it usually takes some action that is damaging.

I'm not here to Apple bash, they make great products. I want to know if anyone has a better way to manage media content on their iDevices that does not involve the iTunes sync process?