Most big chain stores supplier can vary by region. Napa in northeast is East Penn (or was recently) but not in south.
Johnson Controls made batteries are in my opinion the best. That means Walmart among others.
Key thing when buying off the shelf at big store is date code. Buy the newest you can get. Usually a letter for the month and single digit for year.
With AGMs make sure your changing system does not fluctuate too much. Due to their fixed electrolyte quantity you can boil out. They do vent, they have a valve that will release with over pressure. The rating for most is not more than 14.1v to change but slightly less is better. And they don’t do well with deep discharge again due to the nature of the electrolyte.