Hard to say, both have great products. I guess in the end it comes down to your personal opinion / preference.
For both hard and soft product I believe CX might be slightly better.
Since you are flying from Frankfurt LH might be the Airline to choose though in terms of ground experience. FCT is obviously a bonus point for Lufthansa.
If you were flying HKG-FRA only without connection id definitely say CX because of above mentioned slight product superiority.
In any case its not like you've got to choose between say UA/AA F and LH/CX F where it would be quite an obvious choice.