It's true that there are only a handful of battery manufacturers.
As I understand it (and correct me if somebody has different info):
Johnson Control makes batteries for Sears Diehard, Autozone Duralast, Interstate, Costco (is that Kirkland or something like that?) , Motorcraft and some Wally EverStarts, ProStart?, Bosch?, Advance Auto. They also make the Optima brand.
East Penn makes Deka.
Exide makes Exide, NAPA, Some Wally EverStarts, Champion,
Delphi makes ACDelco
Then there's probably several other brand names, but they're made by somebody on the above list.
I always go with the Autozone Duralast because they've been solid performers (knock on wood) and there are a ton of stores in most states I'm driving through just in case something happens.