There are those that say from a sq perspective you would be fine whichever way you choose. If you are still having problems deciding at this point I would think you need to look at whichever player suits your needs better whether it be form factor, functions or aesthetics.
This is a topic for another forum, however I will say in MS's defense that they do not cherry pick what hardware they support like other companies and therefore have to develop drivers for everything instead of a minute amount of selected hardware.
I have yet to have a playback issue. All of my flacks however were ripped from my cd collection with dbpoweramp.
Looking forward to the windows driver, does anyone know if 64bit will be released this week?