Jaguars give you unlimited healers, units for easy worker stealing/sneak attacks and a resourceless general purpose unit good enough to successfully wage classical age war. Relaxed resource requirements and a free promotion that sticks isn't that bad in my opinion... raw power on top of that would not be good for balance. The Phalanx is disappointing and has poor synergy with Greece as well. It would be somewhat more useful in a civ that didn't start with hunting (avoiding that tech is often desirable so you can keep building warriors for cheap garrisons and upgrading). Numidian Cavalry don't impress me either. War Chariots don't do embarassingly badly against Spearmen (sometimes better than NC on a hammer-for-hammer basis!) and are *very* efficient against everything else. NC can do things WCs can't, like prey on stacks of catapults with heavy cover or keep a promotion on upgrading... but against the AI situations where they are more useful than War Chariots are rare. And WCs are already past their prime, having possibly enabled you to eat 2 neighbours by now.