It's a few years since I was there, but I'd say AF is pretty much your lot if you're looking to ship from Europe. The only other traffic I recall is Congolese carriers (Hewa Bora
) and the odd French Herc.
Cargolux do Kinshasa (or did) if that's any good. You'd still be looking to risk it by barge or knackered aeroplane (plus multiple bribes).