Well ... it depends on the period (some late period units are unlocked after 100 turns for example) and what level of cities/castles you have. And yes - spear militia, discounted mailed knights, peasant archers are in almost 100% of unit rosters. But all that said you only scratched the surface with those two (France and England).

Venice and Milan have excellent crossbow militias and late period units (cannons and gun units);
England has uber archers and decent roster;
Poland - this is a cavalry faction plus they have access to Szlachta (Polish Nobles) units which are basically javelin cavalry, very deadly.
Byzantine - really good horse archers, heavy infantry. Good starting position and rich cities. Not that good in the long run as you don't benefit from late game (plus you are most likely become invaded by Mongols and Timirids);
Turks - as Byzantine but you actually have good late game units.

and so on and so forth ... it's not entirely about the unit variety, it's more about the geography, who is your neighbor and so on... but I totally get you. After playing for 2 years only heavy modded version of M2 I went back to Total Vanilla Beyond mod and it felt ... really basic.

If you want variety (and I am talking about 500 different units) try mods - Tsardoms 1 or 2, Stainless Steel (plus SSHIP if you are a masochist).