I've read on a walleye fishing forum where the guy's there love the AGM batteries for better run time, some have stated they get 5-7 yrs out of 'em, usually the cabela's brand comes up as a good one, no 1st hand experience with the AGM tho. A lot of their set ups are 24-26v systems. I've used walmart grp 27 batteries on a 12v 55# terrova for several years now, I can get 2.5 - 3 yrs on mine but I don't pull cranks with the terrova. Battery maintenance is the key to getting good service life from the batteries.
GO BIG ORANGE !
I meant to behave, but there were just way too many other options available at the time.