The ESP Guitar Company

Absolutely RJD, a sweety guy that had none of the Star facades about him.
Check out a new Band, Liliac on Youtube
Their Singer Melody is an RJD style singer, she is fantastic and only 16 or 17 I think!!

Really depends on mood

Dio as a singer,but I like solo Ozzy (up to and including N.r.f.t.w) better.

I listen to Ozzy's music a lot more often than Dio's, but when I listen to the albums they did just with Sabbath, Ozzy's stuff sounds so primitive by comparison. The Dio material sounds a lot fresher and just more musical. Case in point: Listen to the plodding bass on "War Pigs," then listen to Geezer really PLAY on a song like "Walk Away."

Dio for sure. 

Dio had this particular amazing voice range and he was such a nice man, but Ozzy is more fun. I vote Ozzy.

For Black Sabbath, I prefer Ozzy.  But Dio did some great work with Sabbath, and I really liked his solo work and with Rainbow.  "The Last in Line," "Rainbow in the Dark" and "Holy Diver" are some of my favorite songs.

DIO. No doubt about it.........