None of these are useful for anything but the very early stages of the game, so I've considered their utility early on.
In most games, Barracks and Totem Poles gives you 6xp for your archers which means 2 promotions. Barracks alone gives you 3xp, which is only one promotion, but you're also only 1 or 2 xp away from that second promotion. You'll get that easily from Barb raids early on, or if you have the Great Wall, just park some archers on forested hills outside your territory. I usually do this anyway just to get the 10xp max. Also, there's rarely a need for more than 2 archers in your cities during the early game, and it can be cost prohibitive to have more than that. Depending on map sizes, that could mean only 6-20 units get this benifit at all.
Stele is nice if you have a Creative leader and go with a builder strat, spaming early culture buildings. This does allow for some excellent REX, or getting a huge early boost on a cultural victory. Definately stronger than the Totem Pole.
I voted Obelisk since my strategies usually require a great deal of Great People. Knowing that I'll have an early Great Prophet tells me that either I'll be the third or fourth civ to found a religion or that if I capture a Holy City, I can immediatly build the shrine. With a little missionary spreading and spy action, I have a huge boost to diplomacy for most if not all of the game, and usually a huge diplomatic boost. Also, it's easier for me to sacrifice a Great Prophet for a Golden Age than say, a Great Spy or Great Engineer. Becuase these benifits are helpful for ANY type of victory, I rate the Obelisk as the strongest building.
Edit - I forgot, try playing Lincoln of Egypt to leverage the most benifit from this building.
