Best AGM batteries

Nothing against Li batteries, BUT (indeed large BUT) to do them properly, one has to add in the cost of a proper Li battery charger, make changes to wiring so the alternator does not damage them, be aware of their temperature range etc.

If an RV is set up for Li batteries from the factory, they make a lot more sense to me.

BTW, have used Lifeline batteries in our sailboats and motorhomes.