They can't be the best band ever because there is no best band ever. They may be your favorite band but that doesn't mean they're the best band ever. Because music is entirely subjective.
People tend to exaggerate their influence. People say they influenced everything. Not true. They influenced musicians in a way to think outside the box and do something new. No bands really derived from their sound, but how they constantly did something different and weren't afraid to.
The music the hipsters listen to would have existed without The Beatles. The Beatles main influence was in the field of Rock, particularly in the sub-genres of Experimental, and Psychedelic.
Mainstream music is Pop-Punk, R&B, Electronic, Rap, and mixtures of those styles.
The Beatles had a strong influence on music, but only on some of the biggest sub-genres of Rock at the time. As I mentioned above, Experimental and Psychedelic.
They had no influence on Punk which inspires a lot of Rock today.
Steve: Dude, their incredibly overrated.
Mike: Shut up, you're just a 13 year old that doesn't know what the hell he's talking about!
The greatest Beatle song is probably either Blackbird or Yellow Submarine.
Joe- HOW DARE YOU SPEAK SUCH BLASPHEMY! *Pulls out magnum, shoots Billy needlessly*
Please! Get over it!
Bob: Actually I quite like Abba instead
Jim's Gang: Wot did you say??? (about to kill him)
God: Leave Bob alone, we all have different tastes!
Jim: Okay, sorry God