According to the readers of Total Guitar and Guitar World it is. I love these questions and hate them all at the same time. I want to say what about Deep Purple 'Smoke on the Water' or Metallica 'Seek and Destroy' or Rolling Stones 'Brown Sugar' but then someone is going to call me out and say "what about this one and that one"? It's the ultimate rock question amongst a group of music lovers over a couple of cold ones. Have a great weekend and rock on! https://www.blabbermouth.net/news/led-zeppelins-whole-lotta-love-named-greatest-riff-of-all-time/