They are not cumulative, both Wonders work on the BASE science produced. tao posted a pic back in Demogame 4 showing this (
thread and
specific post) We should therefore put it in the city that has the highest BASE value after corruption if we are purely using science output as the criteria.
Projecting up to full population (ie: all availible tiles used) that puts Priapos on 63, Olympus 62, Augean Stables and Berlin at 61, Besancon 57, Styx and Civantonia at 54. Addining Corruption gives Olympus 62, Piapos 58, Augean Stables 54, Civantonia 49, Berlin 48, Styx 47, Besancon 44. Putting the Forbidden Palace in one of these cities would push it back to nearly the before corruption value.
There is one other issue that needs to be considered between Priapos and Olympus and that is the large overlap of the two cities. Both can not reach the full projected potential as it would use tiles that would also be used by the other. Piapos already has Copernicus, therefore if we deny Priapos the tiles, we deny ourselves best use of Copernicus. Therefore in effect Olympus only has the maximum potential of 46.
This puts Priapos back at the top of the list, but what if we take into account the Forbidden Palace? We won't have a second ring to consider as in Vanilla so placement is not as critical, but we don't want it right next to the capitol (ie: Priapos). Looking at the uncorrupted values of more distant cities, Augean Stables and Berlin are both above the Priapos corrupted value, Besancon is only 1 short.
We should also consider the usefulness of the additional Culture, and there Besancon and Berlin win.
But what about build times? After corruption, Priapos can sustainable make 20spt (if one of the forests is mined), Augean stables 17spt, Besancon 18spt (with 3 native Workers joined), Berlin 17spt.
The easy choice is Priapos as we have already committed it to Olympus' tiles, but Berlin and Besancon with the Forbidden Palace as well would benefit far more from the culture and give pretty much the same (slightly more in the case of Berlin or slightly less in the case of Besancon) in terms of science.