I second Jolt and Lady Froggy- if you really likle EU III, then I strongly urge a few(dozen) attempts at Vicky. A lot deeper, with much more impressive economics at play, and a foreign system that seems much more realistic than EU III.

Plus, I have one major aggravation with EU III- the AI, no matter how much money it creates, seems only to suffer from inflation if it wants to- and that is usually just a few minor factions dying to be exterminated in the first place anyways. Especially in Magna Mundi, that puts the player at severe disadvantage, as the player actually has to keep it in check. Thus far, I have not seen the Vicky AI actually cheat, as it does in EU III.