Most batteries these days are made by only a few companies, with whoever is selling them putting their brand name on it. Diehard (if you can even find a Sears to get one from), Autozone, Advance Auto, Interstate, Wal-Mart and many others are all made by Johnson Controls. Napa sources theirs from Exide. Duracell automotive batteries are Deka, who also makes batteries for many of the smaller regional chain stores.
Quality is pretty even across the board, my best advise would be to look for the best price and warrantee, as well as highest cold crank.
