Why not include generation Y as well. Skip a generation, consider the delivery options available, and ask the same question. I am Gen X, but never particularly liked Nirvana, but was inspired the other "Seattle sounds", and period music. PearlJam is still writing and touring, the Foo Fighters thrive, and RATM will have a huge impact again. Pop is a retrospective term availed by those not attentive to culture, but seek to measure it\'s movement; indie, alternative, and counter culture are for those present/involved when ideas change. If volume, variety, and medium are any indicator the answer is obvious, but it is an evolution of possibilities that is demonstrated by music (and other art); the perceptual revolution occurs by agreement, and after discarding the trodden trails of a road oft traveled, gen Y has the best boots.