Well have to be honest here, like some other answers mentioned, the Beatles were incomparable in the influence, impact, quality of songs, popularity etc they had in such a short amount of time (1963–1969). No other band really comes close to this, even during 40+ year careers. The Beatles are the best selling band in pop history – 800 million records sold. There’s no other band or solo act that comes close to that.
Although Elvis Presley comes the closest – his claimed sales numbers are dubious in comparison to the Beatles considering the certified sales numbers are about 50 million less. I would guess that Elvis and Michael Jackson have both sold around 300–400 million-ish records, which would still put them quite behind the Beatles.
Other bands like Garth Brooks, AC/DC, Rolling Stones, Queen, Led Zeppelin, Beach Boys, Pink Floyd, Madonna, Elton John, Celine Dion etc are all behind Beatles/Elvis/MJ.
Yes I know popularity doesn’t necessarily equal the best, but how else does someone measure how ‘good’ or ‘successful’ a band is if not by sales? By sales, the Beatles is objectively the best band, and its unlikely that any other band or solo artist will surpass them.