Kirkland Signature is Costco's private brand. A private brand is usually made by another manufacturer for cost savings reasons.
Johnson Controls makes Kirkland Signature batteries. Johnson Controls also makes Die Hard (Sears), Interstate, Optima (Sprial), etc.
For the price, you can't go wrong with the Kirkland Signature which most likely has more CCA than your oem, and is the LOWEST price around. The built in HANDLE and battery "stool" is also an added bonus!
I used to use Eliminator batteries, but they are double the price, and DO NOT last twice as long...