I find that a couple civs (Japan and Mali especially) get even more mileage out of free inquiry than monumentality, just because japan can get easy adjacency on harbor and CH (without even a river or fish resources, a Japanese triangle of those is +4 harbor, +4 CH) and Mali has that absurd suguba (see guide in my sig on how to exploit that.) Although Mali could also leverage desert folklore holy sites to extreme effect under monumentality, I feel like all that science is just so hard to pass up. For example, mali can push out 2 settlers, build a cluster of sugubas and get +8-10 on their capital's suguba. Drop in reyna with 1 promotion and now you've got +20 science just from that single district. (and +5-7 for each of the other two.)
If they ever make the late game matter,
The sleeper OP combo is Modern era+ Dark Age combo with Robber barons & collectivism cards, and any civ that goes big on IZ adjacency. (Japan, Dutch, Germany especially.)
+100% IZ adjacency, stack with craftsmen, and +25% prod from factories thanks to robber barons. Feel proud of that IZ you placed next to an aqueduct and a dam for +5? Now it's +15. Have a coal plant? Another 15. Let's tack on +25% more because you're such a good customer. It's how germany ends up with +45 Hansas. It's stupid and unfair.