What criteria are you using for greatest singer? If you are using vocal range it is Freddie mercury for sure.
no criteria
i was just hoping to upset a few people by even suggesting it
that being said, i just looked at a few videos and i was kind surprised how far he went into the glam rock n roll style of music, not just one video but several ones and working with plenty of great rock guitarists quite a difference from the jackson 5 days