I have a first-gen Sansa Fuze. I love it, especially for the seamless integration of the miniSD slot. Solid piece of kit, withstood quite a bit of punishment. The connector is an iPod-like flat piece of shit, but that's about the only thing that really bothers me.
Plays FLAC, MP3, OGG, and WAV I think. Radio, video, and picture browser. Audiobook mode and audible support. Supports one single 'to go' mobile playlist, all others need to be edited on the PC. ID3 tag based browsing, or folder based browsing, as well as a hardcoded 'last 50 songs added' playlist. You can record off the radio or the built-in microphone if you come across something memorable. Can be used as mp3 player via ms protocol, or mass storage, or both. I do believe there's a rockbox replacement firmware available, but I don't dabble in that stuff so whatever.
I'd have bought a Sansa clip had there not been a sale that got me a Fuze for the same kind of money. The big display is nice, but hardly necessary.
I haven't heard a single good thing about the newer models, so if you decide on a Sansa, better read up and get a 'good old model'.
Come to think of it, if all you want to do is listen to music then just get a reasonably priced noname mp3 player, they're a dime a dozen nowadays. Unless you really cheap out they are all reasonably useful. I really don't get the concept of spending hundreds of dollars on that stuff. That's just me, though.