Hard to say..I'd sorta lean towards the "E-coated" being more durable but that's just a a guess.
Off topic- I hope they did the cross-drilling right. I know there aren't any drilled rotors that are OK for use on some Chevies (caprices)..the holes aren't done right and the rotors crack. Those are pretty inexpensive rotors so I dunno if I'd trust 'em...a 90 day warranty against cracking wouldn't give me any peace of mind...but that's just me and I know you didn't ask about such stuff
