I have worked with users on Sony NW-A45 devices and we managed to compile working Device sync profile https://www.mediamonkey.com/addons/brow ... 40-series/
that works fairly well. Personally I have been occasional user of Sony for past 30 Years (Walkman, DiskMan, MiniDisk players/recorders, Older Walkman phones, newer Android Phones, headphones, Monitors, TVs) and somehow even initially very satisfied with product I always end seeking replacement very fast till they release something new that catches my eyes.
FiiO Devices looks and work good, but they lack of Support is disappointing. I have personally contacted them and provided them means to whitelist MMA on their devices but unfortunately as said here https://www.head-fi.org/threads/meet-th ... t-14817780
they lacked to give me any reply after I sent them all needed information even I clearly provided them with enough info to even add support for WiFi Sync on devices that supports it. Some users report MMA sideload, we also created Sync Profile that sort of make workaround to FiiO playlist handling https://www.mediamonkey.com/addons/browse/item/fiio-m7/
There are also several devices I have tested and few USB Sound Cards that work with OTG cables to provide external Audio to some phones making them great for listening Hi Res audio with much more dynamics and quality, but right combination usually takes too much money over the budget and more advanced knowledge than needed.
Basically the best approach would be to find show room, take your own headphones and test few devices on high res files and see what they actually support in terms of playlists and managing/reading metadata in files.
Apple devices is complete another story which I would like to avoid, but lack of customization freedom of choice and limited access to devices is main issue for me that do not like to have his toys sit in original packaging and not being able to play with them.