Obviously a battery living in the same space as people should not give off gasses or fumes. So an AGM would be the better choice.
They cost more than Flooded batteries and require no maintenance.
However, according to this page from Trojan Batteries they don't have the reserve capicity of same size flooded batteries. And actually weigh a tad more.
When choosing batteries for my Electric boat, I read on Trojan's web site that flooded batteries will take more charges than AGMs. That was several years ago, and unable to find that info now.
Scan to the bottom of this page for info on flooded and AGM batteries.
This page specifically deals with Marine and Rv Batteries.
Again the Flooded batteries outperform AGM and Gel.
FWIW: The battery inside our home that stays constantly charged by a solar panel
, for emergency lighting
, is an AGM. The ones in the boat, golf cars, and camper are flooded. May go with an AGM next time depending on cost.
I haven't read this new Trojan website thoroughly, so whether or not AGM batteries are harmed less by being deeply discharged is a mystery to me. Maybe someone can supply a source for that information.
Here is another source for comparison of the 3 types of battery. This source does say that AGM batteries are more subceptable to being ruined if the charger is not in tip top shape.
Hope this helps.