There's no one best weapon type. They each have their pros and cons. It all depends on your play style.
I would definitely argue that there are superior weapon types for each monster. I wouldn't SnS a DevilJho and I wouldn't Hammer Agnaktor. Both are doable, but there are superior options if your goal is damage output. --- Cyrus is leading his battalion in Valkyria Chronicles! Tell them you know Dok.