Superior in forms of practicality :P but I wouldn't say protection. leather is a bitch to cut with a normal sword motion, but it's doable. If it's not thick or hardened then you can stab through it easily. Gamberson would be better than Leather. But Mail, you're not cutting mail XD. You can still stab through it... but it's really... really hard. And you'd need a sword designed for that like the estoc to do it easily. Which is why you invert the sword and hammer on em.

EDIT

To make Chain Mail more annoying... it's usually augmented with a Gamberson anyways :P.