I'm sure it matters not at all, but I returned an AGM battery to Sears due to post leakage (which they said was impossible) without any issue what-so-ever and received a brand new one at no cost. Sometimes, the cost of a battery warranty is only as good as its guarantor.
That's not to say Sears is the answer, nor a Diehard, but that you should take into account where and from whom yo're buying, because saving a buck may not amount to a hill of beans if your dud isn't covered.