Alright, I'm basing my opinions on singleplayer, because I'm not in the Warband beta, but I've always preferred playing as a footsoldier, and never really worried about cavalry. Usually, I'm wielding a polearm or two-hander, a bow, and two quivers of arrows. Now, if the lancer charges at me expecting to slaughter me with couched damage, I can sidestep and swing, and hurt his horse pretty bad, if not kill it outright. If, instead, he plays the game of circling around me trying to kill me with lance thrusts I just pull out my bow and turn his horse into a pincushion. Footsoldiers, from my experience, are not totally outclassed by cavalry.