You can best do this by buying an open-jaw LAX-YYC-YVR as a separate ticket and starting the RTW in YVR (this gets you the Canadian price, about 20% less than the US price). Then you can go YVR-HKG-BOM-HKG-JNB-LHR-YYZ-DFW-LAX. The OWE is segment based, not mileage (4 segments per continent except 6 for North America, but only 2 stopovers in your continent of origin). For business class BA is generally considered to be the best (you could also return LHR-LAX and take a separate trip to Toronto using the remaining segments). I think your routing works well for OWE except for the YYC requirement.