I have looked at lithium. No way are they worth it for the RV. For the race car, yes because weight is critical. For the RV, it's way too much money for little or possibly even no benefit.
I have also used the 6 volt deep cycle golf cart style batteries. They were okay, but didn't really seem to work any better or last any longer than 12 volt deep cycle. So now I just buy the cheapest 12 volt lead acid deep cycle group 31 batteries that I can find. The last batch came from Menards for about a hundred bucks a piece back in January. I don't spend any time worrying about my batteries or trying to take care of them like you have to do with all the fancy expensive AGM and lithium batteries. When I have $300 invested in the whole battery bank, I spend my time in the RV doing what I want to do and not babysitting my batteries. When they get weak I replace them. I would not be able to operate that way if my battery were $1,000 plus. I'd have to worry about taking care of them.
I generally get three to five years out of my neglected lead acid batteries. When I'm at home though, I do keep the camper plugged into short power 24/7. The built-in battery charger in the camper has a battery maintainer in it. If I didn't plug it in, the parasitic draw of the camper would kill the batteries.

Different people have different ways that they use their RV and that is a factor. I'm on the road a lot. I don't stay in one place for too long. I have a pair of eight gauge wires from the truck battery to the coach batteries to charge them when I'm driving. I have 400 watts of solar panels on the roof to charge them what I'm sitting still and the sun is shining. I use my 12 volt system in the RV to power an inverter for making coffee with my Keurig machine, and I use it to power the furnace when it's cold, the lights, charging up electronic devices, and my CPAP machine. That's about it. I'm not trying to run a compressor fridge or the air conditioner or anything like that. If I really need to run the air, I use the generator. People who think they're going to cool their RV using an air conditioner running on battery power can plan on spending several thousand dollars on batteries. To pack enough lead acid batteries for that use would weigh a ton, so they're forced to use lithium. I'd rather just run a $700 generator occasionally when I need it.