Best value
Flooded:
East Penn's Duracell branded automotive SLI batteries from Sam's Club
AGM:
Power-Sonic PHR High-Rate or
PG High Energy. (High Rate in an automotive context means it can deliver brief, high current surges - like starting - better than a high energy battery that contains more total energy if delivered at a lower rate for a longer time). Both are industrial-grade batteries with a design lifespan of 10 years (especially the PG series, which is designed for telecom standby applications).
Cost is no object AGM:
Trojan RE series
PowerSonic & Trojan are available in a lot of sizes that automotive batteries usually aren't made in, so check the physical sizes carefully.
Many on here with automotive-centric experience may have never heard of either brand, but don't let that stop you from considering them.
Either Powersonic or Trojan is a better value than the marketing-fluff driven Mexican-manufactured Optimas.
East Penn makes a line of Duracell-branded AGM batteries that are sold at Sam's too, but they may not be quite as long-lasting as PowerSonic or Trojan for deep cycling.
Here's a good example of the cost vs performance. All three of these batteries are interchangeable in the intended application:
Power-Sonic PG-12V55FR (
60 amp-hour @ 20-hr rate, not 55AH as this seller indicates):
$139.49
Optima 8171-767 (38 amp-hour @ 20-hr rate):
$147.05
Exide Edge FP-AGM51JIS (45 amp-hour @ 20-hr rate):
$170+
(
Exide also filed Chapter 11 bankruptcy last year, and
now may be facing anti-trust charges, so don't count on warranty claim fulfillment).
Trojan matches PowerSonic in performance, and has slightly greater deep cycling lifespan... for a higher price than Exide (harder to buy Trojan at a big discount, too).
