depends on what else is in your list
spirit stones and vectored engines are a given(and holo fields on falcons of course)
do you need anti troop?
take scatter lasers and shuriken cannons on your serpents
more anti-tank?
TL bright lance and a shuriken cannon and your serpent is a threat to everything
for falcons pulse laser, scatter laser and shuriken cannon give you the most shots for a mostly anti-infantry platform, but the pulse laser is S8 AP2 so it can kill anythingon the table.
find the gap they need to fill,
hope that helps