I have a new job where I will be traveling BOS-SIN 6 to 8 times per year, but it will only pay for premium economy. I'm AA gold right now and am on track to be platinum by August, which confers OW sapphire status. I may reach emerald next year.

Is there any greater chance of a complimentary upgrade from premium economy to business class by choosing a specific OW carrier for these flights? I could take JL, CX, BA or QR.