I assume you're flying LHR-HKG-CTS?

LHR-HKG will definitely be in the long haul configuration, so expect the Cirrus seat in J - in my opinion, one of the best seats out there.

HKG-CTS probably will have quite a high chance of getting a regional plane with the love-it-or-hate-it recliner.

Food wise, CX is not known for good food. I guess it's all perfectly edible (unless you go for the beef, and if so, then there's really no one else to blame...). A more detailed discussion here.

Tips:
CX perhaps excels most (at present) with its lounges. LHR has the new lounge, comments available here, and probably well worth the visit.
At HKG, you'll have access to the first class lounges with your BAEC Gold - definitely try out The Pier First. I personally have a soft spot for the Qantas lounge if its open while you're in HKG.

Compared with BA/AA, I'll go for CX any time. Food probably a bit less appealing, but everything else, I do prefer CX (price aside, though that point in your case is moot). Of course, not everyone agrees... but please do post your opinion after your trip! Safe travels!


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Edit: just saw your newest comment about flying from Milan. Sorry!