GTW Prometheus S
The GTW-5 Prometheus "S" cannon is one of the best-known weapons of the GTVA. Originally developed during the first Great War, it was temporarily retired due to shortages of critical materials. With the development of gas-mining vessels to extract these materials from nebular clouds, this popular design has been recommissioned.
The Prometheus S is an excellent weapon, boasting high hull damage, high shield damage, and very good range. Almost every fighter and bomber in the Terran and Vasudan catalogs mount this gun. Disadvantages include a moderate-to-high energy usage, and a relatively slow rate of fire that requires patience and marksmanship to line up shots.
Still, the pros outweight the cons. If you're not sure what to take, and this weapon is available, it's a solid choice and proven performer.