In my view it’s not just about the product – price plays a key determinant. Especially, if you’re paying yourself!
All three airlines to HKG offer a pretty good product and it’s a busy route.
If time is not critical I’d also consider some business class options with an en-route change in the Middle East or Asia as there are some amazing deals on airlines with pretty good products if you fancy trading a change for some comfort and better service en-route.
In simple terms, £250 for PE in BA is worth it on a long route like HKG and the comfort of the 380 is superior in most seats to the 777.