I'm not claiming it's based on marketing alone, but I am claiming there is a significant difference in the usability of their products, and that contributes heavily to their success.

I'm certainly not going to be able to produce any studies, therefore I'm responding with actual occurrences which led to me Apple as my final solution. What happens when the linux computers hard drive fails? With an iPad, you tell your grandparents to go buy a new one and put the iCloud log in, and in an hour it's back to the way it was. I don't want to deal with backup and restore, neither do most people I know.

What happens when they bust their phone? Go to the mobile phone store and get hassled by a minimum wage kid trying to trick the elders into more commissionable services? Have them call Samsung or Google 800#, wait on hold, have to do shipping and receiving? Or tell them to go to the Apple store and get it swapped out?

These are all real life experiences that are much improved with Apple's devices. If you can afford it, and are not interested in tinkering, then I can't recommend anything else.