Colosseum - 16 (19-3) --- I always managed quite easily to keep my citizens happy and my culture high. The Colosseum is, for me, a waste of space. Usually, the Entertainment Complex is enough for me, and once I built it, I don't need extra happiness. And the culture boost is... meh, for me.
Pyramids - 9 (8+1) --- My favourite civ is China, because I'm a wonder fanatic. But I was used to the extra builder charge, so the Pyramids is for me a no-nogo. Placed on a piece of land I was not planning to use? Check. Available early with few requirements? Check. Easy to built? Check. The extra builder charge is for me, sometimes, the game changer is tied situation. It's what can make the differend between exploiting both all your resources and build extra improvments without wasting time and hammers on builders that will become more expensive as time pass. So, for me, Pyramids for the win.