I have a Sony nw-e407 and it’s amazing, bought new when 1GB was a large size however you need to use Sony’s SonicStage program to load files on.
It compresses them to a smaller size than MP3 but maintains the quality.
The charge time and battery life are still incredible, even after all these years.
It’s currently on top of my PC case in bits drying out as I was using it this morning during the storms, I thought I’d killed it and started looking for a replacement, but when I rewired the battery a moment ago it lit up so I’ll rebuild it later.
HOWEVER, it’s a very old model and I bought Sony’s replacement type for my daughter about 3-4 years ago and it was shit, but maybe it was a one off?
For a replacement I was looking at the Sony NWZ-W273 water proof ear buds/neck band type thing or an ipod shuffle.
Hope some of this helps.