I played with the standard settings shown here.

I felt pressure when both Kraxis and Resoln declared war on me pretty early. At that point, it's just a matter of surviving the countless waves of low-level troops they've built up.
I chose Path of the Warrior for my sovereign. I used almost no magic because it's so expensive for Gilden. I did cast Nature's Call on him to help lessen the impact of the Kraxis fire mages and Resoln gravewardens. He was able to do consistent heavy damage each battle and survive because of lots of hit points.
As for tech, I used the Magic tree to get golems. Golems are mostly good for taking punishment and not very good offensive units. The AI should probably be targeting them last not first. I used the Warfare tree to get bows. I don't normally go for bows, but when I did a Tech trade with Tarth, most of the points went toward Archery so I thought what the heck. I designed archers with the Charge trait. This seemed to do 12-15 points of damage on their first attack, then they would do 2-3 damage on the rest of their attacks. I did quite of bit a tech in the Civ tree because I felt like it was the only way to keep up with the AI's economy/research.
Speaking of economy, I had a pretty good economy because 1) my first two cities were a 6/3 and 8/2 respectively (with farm upgrades), 2) I built merchants in both cities, 3) I choose 300g for killing the rats quest, 4) I sold a lot of loot early on, and 5) 3 of my 4 champions were governor types.
As for AI, I cut off choke points with pretty weak troops. I think the AI should have done a better job of taking them out. Secondly, once I can get close enough to an enemy city, I just park right outside of it and wait for troops to pop out one at a time and then pop 'em. In addition, once I find an enemy rally point, I have my troops stalk that area and pick off the armies trying to come that rally point. I think Brad should "hide" the rally points a little better.
My favorite play style is to use more magic, but I wanted to try the super sovereign approach with Gilden because I think that works best for them and it did!
P.S. I did use Tremor a couple of times to hold enemy troops stationary until I could get there with you know who.