My favorative military units is siege weapons, a.k.a. the artilleries.
They often leave enemy units with not chance of retaliation.
[For best enjoyability, this reply post should probably stop here, and be short and concise, and pertinent]
[But I rave on]
I am now freshly stepped into a new age, the Early Middle Age, and the Mounted Archers look very cool.
I built a lot of Mounted Archer Range in a go, without experiment first. They are very costly in terms of supply.
The results, not so good! They die easily and takes a long time to re-recruit. No advantage even though I am fresh into a new age which means I am mostly fighting against armies of a lower age.
But maybe it is because I haven't mastered the techniques to correctly use them yet.
Like with the artillery, to learn how to use them, you can first look at and study the Auto Fight.
Auto Fight is not good for player with experience, even a little experience, I guess, but if you are entirely new to a certain type of unit, there is a lot that can learned from Auto Fight.
For example, with the artillery, the Auto Fight always sends the Artillery to the corners of the map. In one corner, they can only be Melee-attacked from two sides, out of the total six sides in total. I had not thought of that before I watch the Auto Fight.
Also, with the artilley (this I learned by myself) pay attention to the turns, and attach the enemy unit that is about to move... how clever! But hey, that is only the "first layer" of the tactic. The second layer (the advanced lessons) is that you don't want to attack the next enemy unit that you can only wound, non-fatally, but rather the next-next unit that you can kill (with two hits, in two turns)!
What is the techniques with the Mounted Archers, then? I think I haven't discovered them yet.