I would say the current meta mobula is hades on the top, artemis bottom hull side and top balloon side, and a carronade bottom balloon side. The last gun (top hull side) I prefer as flare or gatling, but that seems personal preference.
An interesting set of developments more recently is the strong focus on counter and control builds like gat/carro pyramidion and merc/artemis combos in mobulas, pyras, and even junkers. Of course, this is probably just because people got sick of getting constantly killed by f*** metamidions....