In
ToTe both upgrades has the same speed and initiative.
The fire breath upgrade was kept as offensive upgrade - 8 speed and 13 init. Firebreath is useful skill only when hitting multiple units at the same time and this can happen only if you take the battle to the enemy front line.
The first upgrade was made more defensive
-1 init, -1 speed but 20% more hit points and +1 defense. You pick this one if you want more durability and if you know that the battle will occur mostly on your side of the field.