I like Precursor worlds. Gives the planets some unique character (which I had requested before Galciv3 development started). Now, if you had 5 Precursor Prisons on the same map, all with the same ideology choices, not as much. Even then, though, if you have a PQ18 Precursor Prison with Arnor spice vs. another PQ18 regular planet with Arnor spice, both have different tile layouts--you still have some different character to them.