In the whole game the units that required most of the food are:
5 Food: tauren, destroyer, chimaera
7 Food: mountain giant, frost wyrm
We all can see the discrepancy. Mountain giants and frost wyrms feel like “ultimate” units that require too much food and resources. Even units with 5 food, we don’t see that often (except destroyers that are unique dispel provides for UD). In order to see giants and wyrms more often in 1vs1 games, we should rather reduce their food to 6. Of course, hp and price should adjusted. Even with 6 food, these units already will be the most “fat” units in the game.
In the same way, the units with the most armor are
3 Armor: spell breaker, tauren, gargoyle, destroyer, druid of the claw (bear form)
4 Armor: mountain giant
5 Armor: knight
I suggest to reduce knights armor from 5 to 4 and balance the nerf with +1 attack or some extra hp. Human has plenty access to armor via Paladin’s aura and inner fire. Knights don’t need that much starting armor. This way all units in the game with upgrades will have at most 4+6=10 armor.