I would say Apple. If you are trying to rank for one of Apple's products, there will be a lot of competition and they have a huge amount of links pointing to their products (as they are expensive and Apple don't want a third-hand to rank higher than them and steal the customers, the cost per customer can be high as their shit broke every 3 months so you need to get a new charger, headphones, etc.) while Amazon is a marketplace with MILLIONS of products where there are many not building links to their product pages. Sure, some might do it in competitive niches but usually the product pages I see ranking barely got any links pointing to them at all.
But it might depend, as some might build a lot of links or for some pages that Amazon makes a good sum of money.