A tactic to be used once in a day, should not be that relevant, honestly. What much is that gonna give to you? A single big attack for what? War? I doubt an scenario were you are going to need that help to win a war, so I think once in a day, it's irrelevant.
So what should be looked it's the permanent effect, and I think there is little arguing: If you still need resources and struggle to upgrade troops, Notre Dame. No arguing.
If you already overcame the fase resources are a problem, then it's time to change, to the only other two useful and possible wonders (please don't joke with terracota): Colosseum and Forbidden City.
It's true what have been said, that Forbidden City doesn't do anything to prevent a 100% defeat, in the sense it's just another building, not spawning troops like Colosseum, but we should not see it in terms of just victory or defeat, but rather in terms of how big is the defeat.
Let's be honest, there is little chance against a full army mercs planes etc anyways, more with the force close exploit, if you defend one time, you are gonna be defeated after when your traps are broken, so the question remains to get the little damage possible, and there the FC seems to help more, as it makes the quick star victory so nearly impossible if good desing, and makes getting the Town Centre one also more tricky, so saves for sure 1 star, can save up to 2...
Where Colosseum, doesn't appear to be able to do that much, as a base with Colosseum I always think it's still 100% with the Quick Star victory.
Maybe if you had, Acropolis, Colosseum and the Angkot War, that's a viable ultra defensive choice, some top 100 bases have that. Kremlim as Industrial wonder also, and that can probably give the most solid base if traps armed, depending on the design.
But if you have for example already Versailles, it feels like the Colosseum isn't that good, so the pick would be FC: Acropolis Versailles, needs FC, and the Industrial anyone.