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

[RickFGS]

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.

Dont forget that Persia was the biggest empire on earth before Alexander, and RTW focuses after his death and the Rising of Rome in the world, therefore Persia´s potential to become an empire are of course there and their buildings clearly reflect that, you just have to retake Persia´s former glory (Seleucid, Egypt, Armenia, Bactria, Pontus and Asia Minor and you´re done.

The funniest thing is that Persia started as an empire just like that, on the far north mountains of the Tiber and whitin few generations had taken Babylon, Assyria, Pergamum, Jerusalem, Tyre, Damascus and the nile lands...kinda makes you think that what they gained, they eventually came to lost it all , going back to their original homeland...