I would say Prussia has the best military national ideas and Mughals have the best non-military ideas. The other downside of Persia is that you would have to shell out a lot of points for a better tech group. Leader siege would be a better one to grab than Artillery combat tbh. I am currently in the process of making an album of my own custom nation ideas, and would like to hear other ideas and AARs involving custom nations. It's obviously better early because early idea groups are separated by less techs, but since it's not a tradition you need 3 ideas before you even get the reduction and I certainly don't think it's worth a tradition slot.
It's kind of fun to add a bunch of crazy nations to the Americas all at once. Interest per annum doesn't really make sense either, it has too small of an impact.
I would have rated these guys higher but the development changes have in effect nerfed … Monthly War Exhaustion means you end every war with 0 War Exhaustion, which not only lets you do non-stop wars without spending any diplo points, but also remember that War Exhaustion increases coring cost, so this will save you a significant amount of admin points over the campaign.
