Well. It's only on my PC when I'm home (I love to blast the music very loud) and my iPhone when I go outside.
I love my iPhone because I can watch videos and listen to music. So I don't have to carry a extra iPod with my cellphone. It's easy to use and to organize with iTunes and there is enough space IMO for a whole library. If you have an Internet option, you can even watch YouTube videos on your iPhone.
Random, but iPod when I'm going some place or in the house & can't play it loud, computer when I'm on the computer, the radio when I'm in the car & in the morning, & when no one's home, I blast my stereo system as loud as it could go