12 volt sealed batteries, for house bat.Pro/Con

If you never dry camp I'd get the cheapest group 24 battery you can find. It simply won't matter.
Why spend the extra money for an expensive AGM when you don't need it?
By the way, AGM batteries are different than gell batteries. While both types require different charging voltage than wet cell batteries AGMs are almost the same. Just about any normal charger will work with an AGM. This is not the case with gell batteries.
I see no reason to even consider gell batteries in an RV.