Elvis didn't write any of his songs. If you're just singing songs someone else wrote then you're no better than a karaoke singer. The Beatles wrote and sang their own songs and (most) of them actually meant something. Feeling down? The Beatles have a song for that (Yesterday). Need a pick me up? They've got a song for that (Ob-la-di Ob-la-da). In love? They've got a *ton* of songs for that! Further, each of The Beatles had their own persona (John=witty, Paul=cute, George=quiet, Ringo=easygoing) so you end up liking at least one. They also had four movies, a documentary, a Saturday morning cartoon show, and the most number 1 singles on US charts (among many other accomplishments) all before the age of 30.
I like the Beetles a bit more, but that is only because I know a lot more information about them. If I knew a bit more about Elvis I'm sure my opinion would be very different. Just my opinion doesn't count because there is many views and preferences out there.