[Renojustin]

Ah yeah, that's the one.

Sometimes I get carried away and don't reference things.

Wither Bones: Level 6 Thaumaturgy, D3 needed, Area 6, 16+ AN damage, not resistable. Fatigue 50, Accuracy -1.

Dust to Dust: Level 1 Thaumaturgy, D1 needed, Area 1, 22+ AN damage, not resistable. Fatigue 20, Accuracy 0.

So either one can be used to take care of most undead SCs, with Dust to Dust being very easy to research and cast for many nations.

Drain life is a lot rarer so the short answer would be, non-undead SCs are less vulnerable than undead ones. However, undead often come with great perks like Fear or Immortal. So it's definitely a trade-off... if it's worthwhile or not will likely depend on the opponents you're facing, the state of the game, the spread of your dominion; it just depends.