I trust Amazon less than I do Facebook. Facebook lets me see exactly what kind of advertising data they have on me and lets me export all my data. Google does the same. Amazon just shows me recommendations and tries to sell me android tablets full of crapware or sneak their crapware onto Ubuntu. If you've ever worked at Facebook you'll know internally their culture of openness is very similar to Google's "Don't be evil" ...but less explicit. And explicit company values matter, so that is a knock on them. But yeah, Amazon seems worse. Compare their internal cultures because it does affect what direction their products take.
Apple is trustworthy only in the sense that they make hardware devices that, if backdoored, would be terrible for their business. Their cloud services have the same incentive structures as Google so I feel they're fairly equivalent (plus under the hood Apple uses one of the major cloud providers).
Apple > Google > Microsoft ~= Facebook > Amazon.
This ranking encodes:
1. Which physical devices I would trust more (iPad > Fire Tablet).
2. How wary I would be of using their services (e.g Google Search > Amazon Shopping).
3. Whose culture is better for user trust (Google's track record >> Microsoft or Facebook's track record).