Just to add to what others have already mentioned here, HKG-LHR redemptions are actually generally more favorable for AM vs. Avios. Only exception is for Y class, where it is cheaper through Avios if you are able to do off-peak (for BA), and the same if you redeem peak on BA, or redeem on CX (redemption amounts would be the same).

Cut-off for where AM becomes more valuable is generally around the Jakarta/Sapporo/Bali range if flying out of HK. Flight charts overlap so you should double check if you are anywhere within that 2k mile distance, but >3k miles it begins to really skew towards AM being more favorable (particularly for J and F).

If it helps as a datapoint, I had this same struggle (earlier in this thread) and followed percy and others' lead of redeeming most of my Citi points for this 30% Avios bonus. But depends on your travel patterns of course so YMMV