The Homewrecker (Maul) takes only 1 hit for a sapper, while the neon annihilator takes two hits. Also, like Flat said, if you can hit an enemy building, it does big damage. Also the Neon Annihilator has no random crits and needs water on the map to be slightly useful against players.
For Pybros, homewrecker is the way to go. For Pyro sharks, Neon Annihilator.