[Wauthan]

As it sounds like you too favor singleplayer then I can also recommend creatinf a mod were you upgrade the province defence a wee bit. It's an easy and fun mod to make.

Machaka and Pythium, my favorite nations, are a lot more relaxing to play when their frontline defence don't rely on militia.

And I agree with PDF that the map makes a big difference. The Cradle of Dominion rewards a good defence but it can also be very frustrating when it's the AI who's turtling. Kingdom of Karan is a bit more open but still sports various bottlenecks that can fought over. So does the Middle Earth map.