Don't know if this has been done before but here are mine.
1. Sabbath Bloody Sabbath
2. Megalomania
3. Fairies Wear Boots
4. Wheels of Confusion
5. The Writ
6. Hand of Doom
7. Supernaut
8. Into The Void
9. N.I.B.
10. a Hard Road

I've always had a thing for Supernaut. The riff is pure class.

See also - Symptom of the Universe and Into the Void

Another often overlooked track is Mob Rules. Pure adrenalin and classic 'none-more-metal' stuff. It's odd how a lot of the Dio stuff has been erased from history (possibly by the loathesome Sharon Osbourne).

I'm sure people will unearth a lot of other forgotten classics.

umm..every single track from debut to Sabotage?

But seriously, I do adore:

Tomorrow's Dream
Into the Void
Neon Knights
Symptom of the Universe
Black Sabbath
Evil Woman

and Snowblind, which I have been known to declare the greatest Sabbath track ever.

1. Snowblind
2. The Wizard
3. Children of the Grave

The short dirty list.