Elvis has an amazing instrument, and when you listen to the music he wanted to do (ie the spirituals) as opposed to the rock crap, he is one of the most talented pop culture vocalists of the 20th century.
The beatles are incomparable to Elvis because they were doing an entirely different thing. As far as their contribution to commercial music is concerned, they are invaluable due to their inclusion of so-called "world-music" rhythms and styles, and their expansion of techniques and ideas that had not been explored by contemporary commercial music. There was some strong artistry within the group, and an interesting combination and evolution of ideas.
Personally, I prefer listening to Elvis more, I hate the Beatles. I don't love Elvis, but I do hate the Beatles.