The Hessians have a stronger military, the SCRA have a stronger industry and economy. When combined, I'd say it's roughly equal, but the SCRA would surely be able to build a stronger military if they stopped wasting cash and manpower on distant expeditions and all the propaganda.
PS: @Groshyr The Vidar should become a BC, yes, as well as the Praefect. The Hessians should use the Hel as their cruiser and the Sairs should get a destroyer.