Besides Stele and Pyramids? (imo Stele wins by a narrow margin, and only because it actually guarantees religion on Deity, whereas with the Piety tree in BNW, Mayans will still miss it ~25% of the time without Piety/faith pantion/CS/wonder)
Paper maker and Bazaar are very similar, in that they give on average 4gpt per city. Wat's 3cpt is about the same value. Mud pyramid mosques is 2gold 2 culture, so again similar. Ducal stable will average out to the same deal. This is the standard UBs, and they're nothing special.
Special UBs:
3. Candi - +2 to 12fpt. This is not only the highest faith producer in the game, but it also can be built in any city, even if there is no river, so you'll get at least 2 extra GPs out of this if you go wide. This is an absolutely amazing building. Resource value-wise, it is the best UB in the game, by far. Unfortunately, this faith can never be used to actually get a religion because it comes so late, but it can help with spread or great person generation all the same. Coffee house pales in comparison. The Candi is also a bit burdensome to use and difficult to manage (coming sometimes at gold-opportunity cost).
2. Burial Tombs - +2gpt, +2happiness. The timing of this building is so clutch and key for both the gold savings and the happiness for wide empires. It literally changes the game in terms of what Egypt can do, versus what other civs can do. Ceilidh Hall and Satrap's Court come much later.
1. Floating Gardens - +15% food, +1gpt, +2 food for each lake tile. This is a broken UB. It is one of only two +food% bonuses (instead of plus surplus food%), and the other one is in Temple of Artemis, which is the best wonder in the game. All of these should be food surplus if the devs realized what they actually meant to do. If you have an 11-pop city (granary + floating garden) with 2 citizens working bananas, 1 citizen working a lake or river farmland, 4 citizens working jungle trade posts, and 4 other citizens working 1-food tiles, this building provides +4.5 food. By endgame, with a 30-pop city, if you have 14 citizens working trade posts instead of 4, you'll have +8 food per city (assuming hospital as well). These are very conservative estimates, and you can easily get 10+ food per turn by mid-game if you concentrate on food. With the jungle and the NC, this UB really gets out of hand in terms of science/gold snowballing.