There is a lot more in the bonus actions that need to be fixed.
For instance, most classes get a bonus regent action, wizards and sorcerers get a bonus character action. It is a subtle but important difference.
True,
Ranked after how useful I find them as regent action:
1)Agitate. Almost always useful.
2)Espionage. Almost always useful.
3)Wage war. If you are landed you're going to use this action a lot, so 1 GB saved per turn is nice.
4)Trade venture, same as diplomacy. Action saving and money making.. Nice one.
5)Diplomacy as class action allows a regent to spend only a bonus action instead of a realm action. Great savings, but only works when you have someone to talk with.
6)Contest: Nice when you need it.
7)Research.. Research realm spells.. useful until you know the spells you want, then not so much.
As lieutenant action I think I would value Diplomacy and trade venture highest, closely followed by wage war, then the rest in the same order as listed above.