Consider regular flooded 6 volt golf cart batts from CostCo. Best bang for the buck, extremely durable,
cheap. Flooded lead acid is cheaper than
AGM or gel, which don't really have advantages that are so very valuable for our use.
I could not fit golf cart batts into my regular battery boxes, so had to use the more expensive and not as heavy duty 12 volt Trojans.
Nevertheless have gotten outstanding
service from them. I am very hard on batteries as I live on board mostly off the grid, so deep cycle my batts almost every day. After nearly five years of this plus two accidents (run down to dead flat and left for weeks), the Trojans are still going strong without any perceptible loss of capacity. I have no problems with
electrical power.
LiFePo is certainly a far superior technology, compared to our Dr. Frankenstein style Gothic lead acid batteries -- 19th century tech. But I'm in no hurry to change over -- lead acid works well, is
cheap, requires no tinkering or experimentation or home engineering of anything. Maybe by the time these Trojans are finished, the technology will be more mainstream and it will be worth changing over. We shall see.