I buy a lot from Amazon, but it's purely a business decision. If they can get me what I want cheaper, faster or more conveniently than the competition, they get my business. If not, they don't. Same as any other merchant.
But there are a few things which also make me feel good about shopping at Amazon. One is their customer service, which I've found to be far ahead of the competition. eBay totally turned me off once when they notified me that one of their merchants got hacked, but wouldn't refund the payment I'd made - which eBay itself told me was fraudulent.
Another is that Amazon totally disrupted the old model for mail order. Gone are the inflated "shipping and handling" charges and "allow 6-8 weeks for delivery" policies. Without Amazon's influence, that would still be the e-commerce world.
Finally, I really like the tools Amazon gives me when buying. Legitimate customer reviews and Q&A's are enormously helpful, and most listings have pretty good descriptions and photos. Again, eBay falls short in these areas.