Originally Posted by brunos

I fly this route very often with both airlines.

I assume that this is a paid ticket. CX is more, sometimes much more, expensive than BA. But that depends and there will be promotions for the summer.
I do not like the day flight HKG-CDG, but CX often offers better prices if you use that flight. Currently your itin is priced at 3,000 on CX compared to 2,800 on BA. The price difference is minimal and CX is a much better option. BA might offer summer promotions around 2,000 but that is uncertain. Beware that CX pricing is very flexible depending on loads, so fares change quickly.

CX J product is better than BA's. Seat is vastly better, service somewhat comparable. If you fly BA, you have to transit in LHR and that can be a bit stressful and will add four hours on your journey (I like three hours transit to be on the safe side). No fun to land in LHR after a long flight and have to wait for the connection to CDG/ORY. Of course, if you fly to other cities BA might be a good option because if has flights from LHR to many cities or fly into ORY.

You will earn many more avios on BA and 40 more TPs because of the CDG-LHR leg.