I'm a big fan of space combat so I love ship mounted weapons. My personal favourite is probably railguns, in part because they're tantalisingly close to existing. Some of my favourite fictional ships are owned by the Dindrenzi Federation from Firestorm Armada, their ships are commonly built around a core railgun of colossal power, which means that toe to toe their ships are capable of thoroughly wrecking an enemy formation before it can even return fire.
This design also makes their ships look a whole lot more purposeful and imposing than a lot of other sci-fi ships, an opponent seeing a Dindrenzi vessel closing is literally looking down the barrel of a gun.