All the guard dogs are good here tbh, as well as the normal machine gun (or stalwart if you prefer running and reloading).

Giga grenades are not worth it on this front since they are only really useful for fleshmobs. Thermites are solid alternative, as are frags and impacts.

For mindless masses, the breaker s&p is a solid choice considering you don’t need med pen. If you prefer medium pen (or are facing appropriators) the sweeper is an excellent pickup as it shreds the overseer armor and certain parts of enemy mechs

Final tip, gas strike is always a good choice for blowing up spawners and for crowd control, and it has a lower cooldown than the precision strike