1- I would traveling on CX either way (on AA or BA miles). Would there still be a difference between AA and BA?
2- Sorry I wasn't so clear. I would be travelling using BA miles, on AA, hence the east/west rule.
BA has 4 different award charts (at least for the next couple of days).
If you're only travelling on CX, use your BA miles. It's slightly less miles. Even though it will be more taxes, BA miles are about to tank.
If you plan on flying on AA and CX, BA will become very expensive.
CX doesn't fly to HNL, so you're correct that stopping in HNL is not an option.
But that would apply to both AA and BA.
JAL (Japan Airlines) flies HNL-NRT so with AA miles you could fly to HNL on AA, HNL-NRT on JAL and NRT-HKG on JAL or CX.