I would imagine it's more of an 'overall' music. Every decade has good underground stuff, but what matters is if it offsets the awfulness of the mainstream.

In the late 60's the Beatles, Stones, Zombies, Hendrix, Dylan, Doors, Zeppelin, Who, Cream, Pink Floyd, etc. were all mainstream.

In the 00's, thanks to the internet, there has been a much bigger underground music scene with a lot of quality music. However, does that make up for High School Musical being on the cover of Rolling Stone magazine? I vote no.