In my experience with MP3 players, you can almost rest assured that an iPod of ANY type isn't going to sound as good as other MP3 players. Sure they're handy and iTunes is a great tool for keeping track of music and syncing up your favorite tunes (I use it for my iPhone), but sound quality isn't the iPod's strong suit.
Currently, I own a Cowon iAudio X5L, which I've had for a couple of years now. When I was researching players, Cowon's were the ones who always received the rave reviews for sound quality, and I have to say, I completely agree.
The beauty about the Cowon products is the amount of "tweakability" you get on the player to make it sound exactly the way you like music to sound. There are user-controlled equalizers as well as BBE bass boost, which is awesome and I don't think comes on many, if any, other players.
The brand new Cowon S9 looks incredible and I'm trying to decide for myself currently if I want to make the switch to that one. It's actually got an updated BBE+ and has a OLED screen. Look it up on here, it's just recently been reviewed. It looks a lot like an iPhone and has a touch screen as well. The OLED screen should give an amazing small video picture. I'm doing all I can to get myself to hold off on buying one until they have a 30-32 GB version (currently it's either 8 or 16 GB, whereas my X5L is 30 GB).
Anyway, that's just my two cents on your question. If you bought the new S9, I think you'd probably be pretty thrilled with the sound quality you get from it. Good luck in your search!