Disagree re LHR/YVR the loads should be good, every time I have flown BA premium it has always been full and the loads in Club and economy make me think they are little different.
Having made a number of transatlantic crossings on VS and BA in the last couple of years give me VS for a better in flight service but BA for its quality of meals.
Good luck VS and I am sure I will be booking with you soon.