Massed infantry is the best all-around option, unless you know you will only be fighting monsters. (Massed archers/MI are best for monsters.) But trying to tailor your army can be very difficult and frustrating.
One problem is that you can't tell people what to recruit. You're limited to offering an opinion when asked, or generic statements like "our army could use more archers".
A second problem is that many people are going to be hesitant to drop their units and recruit what you want.
I usually ask people once they lose most of their units. It is easy to convince them by funding them a full unit
or assigning militia units.
You just have to give people a good incentive, good enough to make people give up on their captains.
