I want buy because it is lighter than ipod touch and apple sound quality is best
If you are not able to accept the fact that there are better sounding players than ipods, there is no point in opening the thread and wasting others time. Please go ahead, get that nano and be happy. But do note this:
For the price of ipod nano, I can buy Cowon iAudio 9 8GB and a set a of IEMs like Soundmagic PL30 or Nuforce NE6 (by adding just a bit extra). I get a player that plays, wide range of audio formats (including FLAC, which is widely regarded as the best audio codec), has custom equalizer and BBE+ settings that you can use to fine tune the output according to your taste, has FM Radio, voice recorder, better battery life and hard audio controls (so that you don't have to turn the display on every time you want to change track). Couple the player with a quality set of IEM and you have a portable audio that literally pawns nano 6G in everything.
PS: I have used a Cowon D2 and ipod nano 3G so I can definitely say that while ipod nano 3G has very balanced audio quality and none of the equalizers were able to give a good output, D2 gave me complete control on the audio output. It took couple of days for me to get the right balance but it was worth it.