A major advantage is the depth of discharge and the capacity that can be used per kWh. Lithium batteries can usually be discharged up to 95%. Depending on the technology, AGM batteries are already damaged from 50% discharge and should not be deeply discharged.
In addition, a lithium battery weighs only a third of an AGM RV battery. In addition, lithium batteries with up to 3000 cycles have a longer service life compared to AGM batteries with mostly 750 cycles. LiFePO4 batteries can also be charged and discharged quickly without degrading performance. The only downside is a higher price, which is significantly higher. The bottom line is that the advantages of the lithium battery are clear, especially when you include the lifespan.
We, therefore, recommend lithium batteries, but AGM batteries could make more sense for occasional use from a cost perspective.