Ozzy first obviously..Hmmmm. I think the best Black Sabbath songs were when Ozzy was singer. But I agree, of the three Gillan was the best singer even if it wasn't the best era for the band.
And as much as I don't think Ozzy is a great singer, I enjoyed the first couple of solo albums, but I think primarily because he had great musicians with him and there were some great songs.
