Your poll is mean. I want to choose Led Zeppelin because they helped pioneer heavy metal more so than Black Sabbath did at first (early Sabbath is the genesis of Doom Metal whereas early Led Zep is the genesis of heavy metal via Jimmy Page's heavy interpretation of English folk and blues). But then we also have Queen. The greatest arena rock band of all time who also had the greatest vocalist of all time, Freddie Mercury and hold a special place in my heart for a myriad of reasons. From an objective viewpoint, I'm gonna go with Led Zeppelin due to the groundwork they laid, but Queen is a very, very close second for personal reasons. Also, your poll is mean.