Elvis was very entertaining and a good singer. The Beatles made some brilliant music but they just weren't entertaining to me at all and I find a lot of their songs boring as well. I love the handful of John Lennon songs I've heard, though. And "Let It Be" is beautiful.
I don't really need to list Michael's qualities here lol, but... He's the writer Elvis never was and the performer The Beatles never were. No one can step to him with the combination of singing/performing/writing/superstardom. That's really what makes him the G.O.A.T. The biggest thing people use to criticize him from an artistic standpoint is that he didn't play instruments (at least not live), but hell, why don't we go ahead and criticize bands for not dancing then?