Of all time I’d probably pick Blink182 or Nirvana. Kind of lame but that’s what I grew up on. One of my ongoing chores is to clean up my music library so I can get back to only having songs I really love.
Also, I’m a sampler addict. SXSW samplers, Pitchfork samplers, iTunes gives away little samplers on Facebook all the time. I’m listening to a Bonnaroo sampler today and loving it.