Have you though about Warriors of Chaos? They're tough and still fairly manuverable with units like marauder horsemen, chaos knights, chaos hounds and chariots. You're army will be small, but you can add a few units of marauders to bring your numbers up if you're worried.
Other than that, I'd agree with Lizardmen with all that scaly skin. Orcs (or a least gobbos) I find are most mobile when running the other way, but that's why I love 'em.