How about Sony X series / Cowon ?
Currently sold my Cowon S9 for a Clip+ due to it's complicated EQ . Rockboxed the Clip+ and enjoying it . :)
My portable sources (line out) subjectively rank by sound quality based on my experience goes like this:
1) iMod w V-CAP dock
1a) DIY iPod w/film caps
2) S:flo2 (supposed to be better with the 2.3 firmware)
2a) iMod with standard dock
2b) Fuze via LOD with film cap dock
3) iPhone/iPod Classic/Touch
3a) Fuze via LOD with Aluminum electrolytic caps
4) Fuze/Clip HPO to amp
To me the difference is in the detail and space of the sound, which can be heard with better equipment, at least for me.
If you want a large player and don't want to either spend a fortune (iMod) or DIY (my 240GB setup), your choices are the iPod Classic, an old Zune, or the 128GB Touch. Of course, you can get something else like an Archos but per these forums the Archos lacks SQ. Anything I missed or any other thoughts?