AC offers an international business class product (from YVR, YYZ, YUL, YYC, YOW) that is very similar to that of Air New Zealand. The only problem is that one needs to go from LA to one of those cities on AC whose North American business class seat configuration is not much different than UA's North American business (first) class seat configuration. However, most of AC's North American planes do offer AVOD at each seat - business or economy class.

I suspect that AC's price from LAX to LHR is very competitive with the other airlines mentioned above.