The best...

itune provide only low quality music, it's all up to what kind of music you're looking for.

Example for any kind of electronic music Beatport provide highquality to studio quality tracks.

I use a program called freecorder to record my music. If the song is on youtube,pandora,myplaylist(dot)com or any webpage with an address bar I can record it and it has the same sound quality. Its pretty sweet. For example lets say you want Friday all you do is enable the freecorder toolbar then go to the song and wait for the song to load completely then you click on the icon that looks like a piece of old film and it opens a box then you click on the song and it asked were you want the song saved and it has the same quality as the video. You can also save videos just tell it to save it as a video then use the converter it came with to convert it

If you want the entire album use mp3boo and make sure you have winrar.

If you don't rly need it DL'ed,and just wanna listen,use Grooveshark