I've been buying Hannaford brand that's 100% juice with ascorbic acid. Says nothing about preservatives, not sure if there's any in it or not. Some say that preservatives don't harm anything anyway, might kill off any wild yeast I guess. It's alway real active for me in about 24 hours after starting the primary.
I haven't had a problem, started another batch a couple minutes ago..
This time I used 6 can of concord grape juice, 2 cans of apple juice, 3 pound of plain old sugar, and Red Star Montrachet dry wine yeast for a 3 gallon batch. Can't wait to see how this one turns out. I like experimenting!!