I quite like the battle realms games...
They are fairly unique
And the way to make a certain unit is by taking a peasant then training him at one place, then at another and so on till you get the combonation of teh UBER units

Also if you are really into RTS you might wanna give "Cultures" a shot.
Basically you run viking settlements and have to make everything.
For example:
If you wanna make a spearman (the easiest soldier in the game to make)
You have to:
Get a guy chopping wood to get logs.
Once he's chopped wood for a wee while he becomes good enough at it to become a joiner (Put somone else on the chopping wood duty so there are still logs coming in for him to work with)
Build him a joiners workshop
Once he is good enough at joining stuff he can become a spear maker
Have him build spears
While guy 1 is busy chopping/joining/spear making have another guy hunting. (hunting gets food, but more importantly for this leather)
Once he's hunted for long enough he can become a tanner (I think, it's been awhile since I played)
Tanners make leather armour for the spearmen
Once you have a few sets of spear and armour built
send them to a barracks (which you've built)
Send some guy into the barracks an make him a soldier
Making bowmen and swordsmen is harder.
Fighting in that game is solid...I never completed it...
it's still quite fun and should get easier once you get into it...but you really do have to run EVERYTHING!