I use AGM batteries because I hate leaky batteries, it's usually the first thing I do on any vehicle I purchase. AutoZone and Sam's have been good, but 1 deep discharge will kill them. On my RV there is a switch to turn on the radio, but instead of the chassis batteries it's still the cab battery, so it's not being charged by the shore power. I've lost 2 batteries by this switch being turned on, I'm going to rewire it this winter. Just note for AutoZone, the warranty is 3 years full replacement, but you only get one claim per purchase. So if you kill the battery a second time you gotta buy a new one.