I think D3 will be a longer game than D2 in general (despite the developers saying otherwise) but it seems like D3 has a higher density of superuniques too.
Diablo 3 Beta SUs:
1. Sarkoth (Dark Cellar)
2. Wretched Queen
3. Captain Daltyn (I know the spelling is supposed to be old tymey but it reminds me of a yuppie soccer mom's kid)
4. Mira Eamon
6. Lord Dunhyld <-- ghost woman quest
7. Chancellor Eamon <-- for the crown
8. Jondar, I mean JONDAAAAAAAAAAAAAAR
9. Skeleton King
And that doesn't count easter eggs like the Data Miner or Lloigor the Crazed. Add those to the total if you want. My only minor complaint is that pretty much all of them but the Wretched Queen appear in dungeons. SUs in overworlds are fun. I think the Weeping Hollow could use one.
Diablo 2 Act 1 SUs:
5. Blood Raven
7. Treehead Woodfist
9. The Countess
10. Flamespike the Crawler -- removed in LOD but I'll count him anyway.
11. Pitspawn Fouldog
12. Bone Ash
13. The Smith