I just recently tried the Duck & Potato canned and Beasley loves it mixed in w/ his D&P dry. I continue to use the food roll cut up into bits for treats or Kong stuffing and still grate a quarter slice over his dry kibble if I don't have any of the canned.
I think if I had to choose, I'd go food roll because it's soooo versatile and is great value for the money. There's absolutely nothin' wrong with the canned, though. Sometimes I'm just too lazy to carry a case of cans out to the car!