There are three major battery manufactures however they offer many different levels of quality.
Consumer Reports tested 150 automotive batteries in this years test, if there were only 3 batteries available they would have only tested 3.
Best Car Batteries of 2021 - Consumer Reports
Any retailer or dealer that stocks a 2 or 3 month supply of batteries is not managing their inventory properly. We sell perhaps fifteen group 24 batteries each week, with a delivery from the distributer each week there is no reason to stock more than 25 to 30.