The Beatles, hands-down, no contest. They revolutionized music in so many ways, including songwriting, studio performance, studio technique, and pure innovation. Their early days were great, but Help!, Rubber Soul and Revolver ushered in a musical sea change that still reverberates even today. Although to be honest, I feel the better argument (per Mia in "Pulp Fiction" anyway), is the Beatles vs. Elvis. The Stones had their moments, no doubt, but from Satanic Majesties onward, they were just trying to keep up with John, Paul, George and Ringo. The Stones' recent years of crap albums and incessant touring doesn't help their case, either.