We are all entitled to our own opinion I suppose. But ethereal sacreds are very potent, and shadow vestals are very good for early expansion as well as early conflict with neighboring nations. In my opinion you should pump out the maximum number of vestals each turn (determined by how high dom you picked, so you want high dominion). They cost 40 gold 3 resources (thats a gold/resource ratio of 13, which is really high). This clearly suggest that you can get away with alot of sloth if you need the extra points.
When you pick a bless you look at the stats of your units and try to either cover a weakness and/or build on a specific strenght:
Why astral-9/water-9?. Vestals have no armor and low hp, twist fate basically gives them another life. Also the extra mr will make them very hard to use banish on (cover a weakness). They also have very good starting defence so adding more will be very potent, thats why I would go with water-9 as well. Also you can pick this bless with an imprissoned oracle rather cheap (compared to a fire-9/water-9 bless).
As for scale order is critical, you want more gold simply. rest is probably up for personal preference.
You can of course go with some high production build and not build vestals, but it seems like a weaker and less effective build for me (but try some builds out for sure, and pick what you find most fun).