Do I need an AGM battery or will a standard flooded battery work?

If your vehicle has automatic engine start-stop or significant electrical accessory loads, an AGM is effectively required — community mechanics on r/MechanicAdvice are blunt that swapping a flooded battery into a start-stop car will kill it within months. For older non-start-stop vehicles a quality flooded battery is fine, but AGM offers better vibration resistance, faster recharge, and longer cycle life.