Surprisingly I usually go for the light cavalary. With those longbowman and swordsmen you simply don't need a heavy cavalary to assault the enemy. Just rain arrows on them and let your swordmen finish the rest. The light cav can destroy enemy archers/crossbowmen and catapults and such stuff after the melee has begun and if the enemy still fights after that, those hobilars can perfectly charge in the back of them.
For enemy cav you have your spikes. Or you can always focus your arrows on those units.