The point is that a Banshee serves a very different role from an Orion, which again is different from that of a Cronus. The Banshee's mass serves it well in melee, and it would be a beast if armed with weapons that compliment that role, but it would be a waste of tonnage and maintenance cost to use it as a fire-support unit where the Orion would serve, and an Archer would excel. The Cronus would fit in with a lance designed for hit-and-run tactics, plugging holes in a battle line, or exploiting a weakness in an opposing line, but it's not geared for a stand-up fight against a line of heavies.
It all depends on what the rest of the lance is designed for, and how to compliment or support that role. I can't tell you what you should get, because I don't know what you want or need.