Damier. I think epi will be too big and stiff in a 30. I own a Damier 30 and if it weren't canvas, it would drive me nuts because I find it pretty big and bulky anyway. I own the epi red speedy, but in a 25, and I think it is the perfect size for an epi speedy-- halfway between the canvas 25 and 30.
In short.... if you want a 30, I'd get the Damier now and wait on the red epi.