It depends on your budget. If you can afford, get an ipod. Its slick in design, and looks trendy. On the other hand, you can get a 30GB zune for about 75 bucks these days whereas you will have to pay more than 250 bucks for an ipod with similar features. You got to understand that zune is bulky, and  looks more like a transistor. But again, you can tune in to different radios in zune and  it does have wireless as well.
$75 zune plays all the major files including videos...so, do we really need to spend $250+? It is about your taste and ability to afford the amount.