I have a trust in Amazon that goes well beyond the rational. If something isn't for sale on Amazon, I probably won't buy it. If I purchase with Amazon, it'll show up, it'll work, and if I want to return it, it'll just happen. I've had one or two issues with their Indian customer service via chat, but any real issues where I ended up getting on a phone, it got solved straight away.
I deeply and truly believe Amazon is on my side, where I believe Paypal is actively out to screw me.
I will use this service wherever I find it.