i've own a sansa e260 for half a year and erm, sorry i know that this is an audiophile forum, but i really can't compare it's sound quality with other mp3 players since i never had any other players to compare about, but i din think that it sounded bad with my UM1.
Pros:
1. large capacity (up to 8gb and expandable to 12gb with 4gb micro sd)
2. video support (but u'll have to convert them to .mov with their program, and really, that gives crap sq for their videos)
intuitive scroll wheel (but some pple juz hates it, depends on individual)
3. can be rockboxed (but beware of ur warranty, though i dun think that the sandisk pple will noe wat u did with it if u delete the rockbox firmware b4 sending for repairs if u need it) (and rockbox can't read the micro sd yet)
Cons:
1. Slow loading time, like 30 sec? they always reload the database whenever u on it, and the time really depends on how much u stored in ur micro sd
2. incomplete support for unicode. what i mean incomplete is, it only shows those japanese and chinese and korean characters when u use the jap/chinese/kor interface for the whole player's menu and etc, and if u use the english menu and etc, unicode becomes boxes. fine with me though, i can take chinese interfaces.
3. inability to charge and play music at the same time. actually this depends on the player, which is a very random thing. my player can play and charge at the same time, but it seems like not everyone can.
4. no support for FLAC and OGG and APE lossless formats (unless rockboxed)
if u wan more info on this player, there's alot of tips and discussions over at http://www.anythingbutipod.com/forum/forumdisplay.php?f=9 and http://lodist.com/forumdisplay.php?f=4
for sound quality wise, a few of the posts would suggest players from cowon iaudio like the D2 or the meizu players for sound quality.