I would go with Flame Body. Volcarona is pretty frail; so a burn happening would be life-saving. Smogon recommends this as well. However, I do see that you don't have Roost or Giga Drain on this set. Without recovery, Swarm could be pretty useful, especially if you get hit while setting up Quiver Dances.
Overall, I'd say go with Flame Body, but it all comes down to preference.