[Norma J]

MP3 player: Commuting etc.
Compact Disc: House or automobile.
Vinyl: House, for when I find a specific or interesting record when I'm scowling through secondhand record stores. I rarely (if at all) buy new vinyl. If it's a current band, then I'd prefer CD as most of the time they produce the sound for CD. If it's old bands, like jazz records etc, I prefer vinyl. And it's a great feeling finding vinyl/cd's seconmdhand.
Tape: Tape stuff off the radio, or listening to old tapes I bought when I was younger. Don't buy them.

I use all forms. I must say though, that I prefer analogue as opposed to digital when it comes to recording.