I've just had such great luck with GC batteries and they're cheap! They last us many deep cycles (years) longer than the 12V group 24/27 batteries I've had. Also, they seem to produce more usable AH even when AH specifications of my parallel 12V were near same. Plus I already have a watering system for GC batteries
Have I considered other battery types? For sure!
have even built a near 12V LiFe pack when I was building electric bicycle batteries. The problem here was that I had to rig up a different charger for them and the over-all cost was REALLY high! Great power though! Easily usable through a good 70-80% of the stated AH capacity with no noticeable loss after a couple years. When we sold that RV the LiFe pack got repurposed to an alternate energy project where it got serious daily use for a few more years.
On paper AGM was theoretically easiest/best I thought for RV use. Though I experienced short usable RV life with 2 different AGM attempts. We mostly dry camp so the battery performance shows up pretty quick during fall to spring cold 3 day outings.
Gel - was weak at the end of just 1 season (bad charger matchup likely)
AGM - noticeably reduced capacity at about 2 years each set (PDI 3 stage charger on one batch)
A set of GC batteries watered quarterly typically last us at least 3yrs till we sell it and get a different RV. The last pair was still going strong after 5yrs when we sold that RV. Actually I don't remember GC batteries failing to provide our typical 3 days of power use while we owned them.
If I thought double the cost would actually buy me less maintenance or comparably longer life I'd jump on the technology. The problem with the Axis and some other RVs we've had, is battery compartment height and/or width conflicting with battery capacity I'd like to achieve using any current standard size options I've found within a reasonable price (proven RV successes too).
Running out of power unexpectedly is something I really dislike. The factory batteries in our current RV have supplied our 3 day needs so far but will they continue to do so for the long haul? A nice inverter sitting on my bench could be the catalyst that leads me to different batteries before finding out how long they might last ...