In my mind, music peaked in the early 90s with the whole grunge thing. For my parents, it was the 60s with the Beatles and the Stones so its especially exciting that The Beatles are being pitted against Nirvana in the latest round of guitar games.
Activision have announced that Nirvana feature as a playable character in Guitar Hero 5 in direct competition with MTV's The Beatles: Rock Band which is released at the same time.
Of course those of us wearing the ripped jeans in 1991 would prefer Kurt's gang over George Harrison's, just as i can assume anyone who was sporting a mop-top in 1964 would take Lennon over Dave Grohl. That's as expected but to compare the two, and to pose the question who was best, is just silly.
Given the choice, i would take Nirvana's music over the Beatles every time but in almost every aspect, the Beatles knock Nirvana into a crocked hat.
If you compare their influence, longevity and record sales, Nirvana are not even in the same country, let alone the ball park. I would take Kurt over Paul McCartney, 'Nevermind' over any Beatles album and 'Smells Like Teen Spirit' over any Beatles single but then anyone of my parents age would do the opposite and that's how it should be. The Beatles were of their time and Nirvana were mine, both had decent songs and both have stinkers.
Asking 'Who was best' is completely subjective and depends on the age group of the person being asked. I imagine if we asked today's kids they would say someone like Coldplay, so let's not ask them. They're obviously idiots.
If you are after the band with the greatest impact then i would suggest the next game is made up of Sex Pistols songs. They kick-started the whole punk movement that influenced most of the guitar bands on the video games today which leads us back to Nirvana who were arguably the best thing in the 90s in terms of music and impact, but best ever is stretching it.