I actually quite like AC's ExecFirst product and I actually find the seats to be comfortable. The cabin is not as elegant as SQ, BA, or CX but between YVR and LHR the only competition directly is BA.

I find BA's New Club World bed to be too narrow at the shoulders (and the seat is narrow too) and when fully reclined I had to sleep on my side in an awkward position. I thought that this is what it must feel to be placed into a casket!!

You could fly BA First but the flat bed is only marginally wider than in New Club World but it is a fairly costly option.

LH can get you to LHR from YVR via FRA and their new J-class has those angled seats which many report cause deep wedgie syndrome. And I really did not like connecting/transferring in FRA either......

You could connect through the US but perhaps Virgin is the only really superior choice? I think AC's Int'l J is better than UA's Int'l J and transferring through the US is, for me, inconvenient. But SFO/LAX to LHR is your best bet if you are dissatisfied with AC J? Or hope that CX gets rights to fly JFK to LHR so that you can fly CX to LHR via JFK (their J seats are also on an incline like SQ, LH, AC 345).

For me, I am quite happy on AC J, and I am looking forward to my flights home in March. At this point I am just grateful that I was able to upgrade into J using my certs.