AGM batteries are a commitment price-wise. Our previous coach had 8 house batteries, I spent 6 years checking and adding distilled water (a big fat headache) before I switched to AGM's. We got to enjoy the new batteries for 1.5 yrs. before we sold the coach.
I wish I had changed to AGM's the day I took the coach home. No more watering, no more sulfating and my lower back sure thanked me. I had to clean the slide-out trays and battery posts every few months. I had the battery trays repainted at the time the new batteries were installed. After that, the battery compartment stayed new looking.
Go with AGM's if your wallet can justify, you will not regret it.
Safe travels,
MM.