Best site for LEGAL MUSIC downloading??

I'm not looking for the cheapest, I'm looking for the best site to legally download music. Please do not put Limewire or Ares or any other P2P music site. All of these can lead to illegal downloading and I am not into that. I'm looking for a site that is compatible with my iPod where I can pay a monthly fee or a flat rate. Help please? I've been researching this for a couple of weeks and have not come up with a great music site. Thanks!