My AGM house bank experience is mostly with 12V g31's, mostly East Penn Deka (also sold at Sam's Club under the Duracell label - current price $155 until December 24).
House bank (2 x Deka g31) on my 26-foot cruiser lasted 11 summers, anchoring 65-75% of the nights. After that it had Sears Die-Hard (Odyssey) g31 AGM's for 4-5 years before I sold it.
Installed 4 Deka/Duracell AGM's for house bank on Dream Catcher two years ago, with 2 for start bank, and 2 for bow thruster/windlass. There's an Optima g31 of unknown age (at least 3 yrs) for the stern thruster. All fine so far, but no meaningful longevity data yet. BTW, the start and bow banks I replaced were each single Deka 4D Gel's, original equipment in my 2002 NT37, just beginning to die after the 2016 summer season.
Had a pair of Optima spiral-wound AGM's which lasted 10 years starting my diesel pickup tow vehicle, including sitting out in Northern Utah snow every winter. When they were 9 years old, I left the truck parked for a 3.5-month summer cruise of BC. When I returned, they easily started the truck's big Cummins. The truck has sat waiting for me to return from a 2-4.5 month summer cruise for ~18 years, and was never hard to start. Right now it has a pair of Deka g34 AGM's, about 6 years old.
A pair of Optima's for starting the 26-footer's Volvo diesel lasted 6-7 years.
Both boats had good externally regulated alternators, and battery monitors. Both would charge at .3C or a bit more if the house bank was discharged down near 50%.
One might suspect I like AGM's.