[Fish n Jeep]

Conventional lead-acid batteries are generally a "you get what you paid for" item. The more lead, the better, which means a heavier battery in the same group size will last longer than a lighter one. Walmart batteries are generally easier to carry than name brand ones for a reason.

I can't speak to AGM batteries since I have never owned one, but the Optima spiral cell batteries are pretty damn good if you can find a deal on them.

Oh, and depending on how your batteries were wired, an internal short in one battery can take out another battery if they are wired in parallel. And sometimes a battery gets so completely drained that it won't take a charge regardless of age.