which faction have the most strongest system that bring them most income?

[guineawolf]

This may sound ridiculous, but I, building-wise, feel that it may be Parthia. Although they may start out poor, and never get any richer, if they were to manage to expand they could be very wealthy. They have the "Justice" line of buildings avaliable to them, to counter-act corruption, as well as a "Trade Caravan" building line which provides extra trade to their cities. Their temple also grants a brilliant law bonus which, as said, can further reduce corruption within the city resulting in an even more bountiful income!

Sadly, since Parthia is such a deprived nation at the start, they never get to take advantage of these premium luxuries which ruins their life chances as a faction - often making their potential riches unnoticed.

but,first Parthia got only 1 temple(temple of Zoastra,and Priest of Zoastra gives only +1 influence,+1 management,+1 command,never gives law bonuses,you can only gain +3 law bonus from Torturer(retinue from Secret Police Network=SPN).Even that Priest of Zoastra can help increase your city public order by 5% and give extra admin income.
I agree with your opinion about their buildings,Parthia can be very wealthy from them.
Temple complex of Zoastra and SPN can give up to 45% law bonus that can cover very far range of empire(cities got distance to capitol)

can further reduce corruption within the city resulting in an even more bountiful income!=can make sure lesser pipe being broken forever....or more "water" supply you can get!