I have not had good luck with WalMart batteries.
I also hate sealed batteries and have had a few work poorly, only to PEEL back the hidden filler openings to find they were low on acid. A refill, and they were good to go. Seems that a lot of the "sealed" batteries are just regular ones with the fillers covered and inaccessible. They still lose juice, unlike a true sealed battery, like the Optimas, which I run in my diesel. (Yellow tops, AWESOME, survive a nuclear attack)
What DOES work really well is the BatteryTender device. It prevents sulfation (they say) and keeps the battery in good shape. Since I started using it I have had no battery failures. There is a Jr. model for less than $30 that works well with batteries that have a charge. This is a battery maintainer that will only do VERY slow charges. it is designed to KEEP the battery up, not as a quick charge. Perfect for long-term storage.
Remember, once a battery drops below a certain voltage, 11.89V, it can become unrecoverable! Best to NOT let them discharge.
Scroll most of the way down for a chart of voltages.