I vote for Modest for a change. Timid was the one we had last time. (Also I have another Timid one that's very efficient against the Maison, spamming Eruption - so yeah, kind of a selfish reason haha).
Most Pokémon that are would-be targets of HP Grass are bulky Rock, Water, Ground, which are most likely slower than Typhlosion.
An extra SpA boost from Modest (possibly coupled with Specs) would be nice.