Even though I am going to stay with my choice of Queen, I agree that individually Kiedis has a very entertaining voice...but then again, there are an abundance of artists that are just phenomenal and can inspire different emotions just from their respective sound. That is why I feel a bands harmony together, the build up of talent around that one awesome voice, is just a really awesome thing.
Some time ago some of my college friends and I had an in depth argument over what band has the best vocals of all time. One of them thought the Beach Boys, hands down, due to their smooth and relaxed Calfornian harmonics. I thought I heard just simple melodic sounds though Anyway, I really think the answer to this one has to be Freddie Mercury and his awesome band Queen. Put together it really seems these guys did have a great vocal output. Who in your opinion should top this list...remember any band, any time period?