Some of the best ''world music'' happens when local styles run away from home. The slightly oversweetened ''World Reggae'' favors Bob Marley-style old-school sounds over modern digi-boom, featuring both vets (Anglo-Indian dancehall pioneer Apache Indian) and newcomers. The best, like Cape Verde's Maria de Barros, bring their own regional flavor to the mix. Ditto ''African Rap,'' which looks beyond the well-developed Franco-Senegalese rap scene to Tanzania (the ruff, Arabic-flavored X Plastaz; Das Efx fans Hard Blasters), Ghana (Reggie Rockstone, who lets rip over pitched-up Fela Kuti samples), and elsewhere. THE BEST OF THE AFRO-RAP REST Senegal's Daara J aren't on ''African Rap,'' but their new Boomrang (BMG France) shows them to be among the best of the new Afro-hip-hop crop.