Spear: I'd say generally more useful for dragoon because their damage is more cooldown dependent than monk's damage but both have a decent amount of cooldowns (most of which should be on cooldowns 15-20s into a fight).

[USpire:[/U] Any time either class is doing aoe damage especially but both have decent tp regen so it's generally not needed unless it's a prolonged fight w/ minimal down time. In that case, it's about the same because monks attack faster but dragoons have larger tp costs on their weaponskills.