I'd have to go with Longevity. It should be called Starvation since that's what it puts most of my cities in. It might be a good bonus in the early game when a lot of your city tiles aren't used up, but in the late game it's only useful if you're on an ICS/domination mission, and even then your newer cities tend to be fully terrain-improved and growing fast anyway.
Second place to Theory of Evolution. The two times I've built it it's given me at least one dead-end tech from a previous age. Pales in comparison with goody huts, trading, scientific civs that get three freebies, and esp. wonders like Smith that allow you to crank up your science rate.
Second place to Theory of Evolution. The two times I've built it it's given me at least one dead-end tech from a previous age. Pales in comparison with goody huts, trading, scientific civs that get three freebies, and esp. wonders like Smith that allow you to crank up your science rate.