I picked heart of the wild as my lvl 90 talent and never changed it so far. A flat 6% INT bonus seems better overall for me compared to Nature's Vigil, a 3 min CD that only server to increase the power of our already weak hots. Since it is based on percentages, it will not impact hots as much as it would a direct heal(Such as a pala's). At least that's what I think.
That's why I am waiting for you to contradict me and make me want to spec into this talent for some fights. Is there a particular fight where Nature's vigil shines over HoTW? My gut instinct tells me it's long fights, such as Will of the Emperor, where the ability can be used numerous times during combat.