THE BEATLES most definitely ♥♥♥
Led Zeppelin is great too, but, give me thumbs down if you want to, The Beatles is the best band in my opinion. They're ahead of their time, created uniquely beautiful and stunning music through experimenting with different genres, music no had ever heard before, and pioneered most of the musical techniques that are still used today. You can't just simply define their music by one song because it's different in every songs.
I have many more reasons, but I don't want to sound preachy, so there. :)
The Beatles forever :) ♥