I really liked Piety in BNW! My beloved Byzantium got a nice buff from this. Civs that might synergize with the tree:
BYZANTIUM: for obvious reasons. Getting the pantheon bonuses from other civs and a reformation belief on top of your extra belief is going to be very good. Add to that how this tree makes founding a religion easier.
CELTS: well, you've got a faith based UA and a faith based awesome UU, why not? I would love to make a War Religion as them. Things like Just War, Holy Order, Religious Fervor, the barbary missionary conversion could help
ARABIA: I was thinking about the Grand Temple on another thread, as it will make for an incredible amount of pressure from trades, I guess. Could be nice to get a better religion overall.
MAYAS: super shrine strategy! A Mayan Pyramid with the appropriate policies and beliefs might give: 3
, 2
, 1
, 1
, :1c5happy: and is built in 50% the usual time. Great! As the Mayas rely on GP buying (Long Count increases GP costs), the To the Glory of God reformation belief will be very useful for them. Jesuit Education too.
ETHIOPIA: well, their stele is very good, and Piety might help their religion. I wouldn't start with this policy tree as them, though.
SONGHAIS: super temple strategy! A Songhai Mud Pyramid Mosque with the appropriate policies and beliefs might give: 3
, 4
, 1
OR 2
, +10%
and is built in 50% of the usual time, besides the lack of maintenance cost. Also, the Converting Barbarians reformation belief could be useful for them: convert the barbarians around a camp and take it for 75
with the recently converted units!
EGYPT: super temple strategy! An Egyptian Burial Tomb with the appropriate policies and beliefs might give: 3
2
OR 1
, 4
,+10%
, is built in 50% of the usual time and lacks maintenance costs.
Indonesia: candi says it all.