I disagree with Largesse being low priority for WHM, as it takes effects on HoTs and Cure III which is where WHM's main source of healing comes from. It's much more useful than something like Esuna that is only useful in very few situations, 99% of them requiring your party members getting hit by things they shouldn't. My personal picks are: Protect (if my co healer isn't carrying/for dungeons), Cleric Stance, Swiftcast, Lucid Dreaming, Largesse, Surecast (swap protect for this after cast).