U2 emerges from the dark days with a gorgeous, confident and inspired explosion of sound. Their first song on their third masterpiece, Beautiful Day may not be the best song U2 ever recorded, but it's certainly their most important, that's fairly non-debatable. The song that firmly re-established their "comeback", made them the biggest band of the world, again, won back old fans, gained legions of new ones, and and set the stage and tone for the next ten years. Just how critical this song has been to U2's career can't be overstated.
On its music merits alone, it's probably 9, but because, like One, it holds a unique place in U2's catalogue, giving this any less than a 10 is probably sacrilege.
A beautiful, green and blue, mentioning China without stocks, 10.