Mekhus in a 4-gun bank if I have it, Prometheus S otherwise or on Terran ships. I never take equal weapons in a 4+2 configuration; firing from the larger or both banks has the same dps. Instead, the second bank will get some long range stuff... Maxims if compatible and I want to take cheap shots at capital ships, Morningstars otherwise.
Tempests in the smallest bank for some added punch at close range, to compensate for the lack of Kaysers (which I don't like because of their energy demands).
If I have another bank, I'll load it up with Trebuchets... long-range stopping power and decent anti-subsystem use.