I was in Francophone central africa from '00 to '02 (Cameroon) and Congolese music was tops in the region. Mostly newer stuff, Koffi Olomide and (convicted people-smuggler!) Papa Wemba, though you'd also hear the older stuff, Franco, Rocherau, etc. blasting from bars pretty regularly. "Radio Trattoir" is my favorite Franco album, though he put out hundreds and I've only heard a fraction of 'em. "Mario" is maybe his best tune.
All the people/groups that Woebot mentions are great. One song I really loved, a hit in the '70s that I don't think has ever been reissued is "L'argent appelle l'argent" by one Pamelo Mouanka. A re-make by a Cameroonian was a big hit while I was there. The newer Congolese music is pretty great too, but has a very different feel than the '70s stuff. Faster paced, much harder rhythms.
Anyhoo...I've been checking this forum for ages, finally decided to join up. Always great stuff going on here!