If you can get your hands on one then the iPod classic is probably the way to go. With the massive storage sizes it’d keep you going awhile. I’ve had mine for going on 8-9 years now and it’s still working great...
The only problem is finding one since Apple discontinued them.
I'd recommend the iPod Classic too. I love the fact that I can have my entire music collection in my pocket. I've had the 160gb version for at least 10 years and never had a problem. It still holds its charge really well and they're really well built.
I've always fancied a FiiO. They're supposed to produce very good audio quality and they take a microSD card rather than having internal memory (so you do have to buy one separately, but that does mean they're upgradable unlike an iPod). They can also play pretty much any audio format you can throw at them including lossless formats like flac.
Until then, I'll work on bringing my disassembled 12 year old iPod back to life with a ZIF SDD (and probably a new battery).
I have a Sony NW-A35 (Walkman branded but not a traditional Walkman) MP3/AAC/FLAC player. 16GB internally but I've put a 128GB SD card in it. The firmware I had previously on the player did sometimes make the music at the start skip a little. Hoping the latest firmware fixes that (haven't actually tested it yet).
Pretty much does the need of playing my music (and the odd bit of radio when needed). If I need anything more than that I can just use my phone.
I'd go with the guys recommending the ipod classic, I'd have to take a look at them for it to be a solid recommend though
A lot of people stream everything now though, all you reall need these days is a modern phone, a few gigs of memory (possibly an sd card) a good pair of headphones/earphones/earbuds and a good music app, poweramp plays anything I throw at it, but it cost me like £5 to get the full version, still for most people that is cheaper than a new ipod