I bought only from Costco for many years. A great warranty that was total free replacement if within the warranty period. It's not nearly as good anymore. Warranty period much shorter than it was, and I think they pro-rated the refund even within the warranty period. That said, it is still as good as anywhere else.

I bought my last two batteries ar WalMart. I went with their tio of the line, AGM batteries (absorptive glass mat, like fancy Optima batteries). Price was fair, certainly more than cheaper flooded battery options, but good for an AGM.