I voted Military. Ok cheap barrracks and more chance of promotions but its not that useful in terms of getting ahead in the game.
I agree, I've never had much use out of the extra promotions, and barracks are cheap enough already, I never build walls. The only thing that makes this somewhat nice is the cheap harbors, it allows you to et up commerce fishing towns more easily.
I find that cities generally grow too fast anyway for improvements to get a benefit along with happiness stuff like luxes and temples and the like, and I wind up with a lot of unhappy people if they get big fast.
I've never understand this attitude, how can a city grow too fast? If a few of your cities grow large, and you don't feel like wasting commerce on your whole empire, just to keep only those few big cities happy, use specialist in them. Specialist will both not be unhappy and they slow down further growth.
But better is to just turn those fast growers into settler and worker pumps.
If most of your core cities are about the same size, what you gain from the high population, is more than what you spend on the lux slider.
Either way, I've read this "my cities grow to fast" complaint before, but never understood it.
Its a kind of like, not accepting a salary raise to avoid paying more tax.
Sure with a higher income, you'll have to pay more tax, but you'll still get more money in the end. Its not like your net income decreases if you get a high enough raise.