Diamond Dave never had a great voice, the best singer in VH was Anthony, that being said he was a STELLAR frontman.
I have seen Ozzy on multiple occasions and while he sounds terrible compared to his peak, he always has an amazing band behind him and the shows rock. I have never seen VH live but I will go to this tour if they come to the DC area. I want to see EVH shred.

Yeah that was the best Ozzy performance I have seen in years but the highlight was Tony Iommi and Geezer Butler. I saw Ozzy's "No More Tours 2" show this summer and he sounded good but Zakk Wylde stole the show.

If Ozzy had people singing for him at the last 2 Sabbath concerts and the No More Tours 2 show, they did not do a good job. I had good seats for all of them and it was definitely him singing. Voice cracking on notes, coming in slightly early/late on a verse, cracking jokes... it was him. Now when I saw Sabbath at Ozzfest in 2001 there was definitely someone singing with him. He would be screaming "LOUDER!!" for the 587th time while also singing War Pigs... He was far from sober in that period, he has sobered up significantly since 2012.