Is Beijing and Tokyo your only reference to this? I agree the cabin size helps for a better service on the 777 but the reason for the question is that I find Asian crew tend to provide a lot better service.

I almost always get better service DXB-BKK than MAN/LHR/LGW/STN - DXB regardless of aircraft type.

I only do TUN two or three times a year now but that is probably the most appalling route in terms of service and that’s always been 777.