The Perfect Linux Distribution
juliette.page
juliette.page
My answer would be macOS. I realize that's based on Unix but it should be the template for how to make an easy-to-use Linux desktop. However, the ability to infinitely swap out parts of the OS means that, practically speaking, unless a very large entity came out with a standard desktop distribution that was macOS-simple but a full Linux distribution and enforced commonality I don't think it will happen.
An example: if you get two or three "gun people" together and ask them what the best AR-15 is you'll get a fierce debate of bands, parts, customizations, etc. Like Linux, the AR-15 is a platform where every single piece of the gun except for the "stripped lower" can be swapped and replaced (not unlike the Linux kernel). Go to a civilian gun range and it would unlikely to find two AR-15s build identically. However, if you visited a military gun range every single M-4 will be built with identical parts.
Bringing this back to Linux: in my opinion, it would take a large, inflexible bureaucracy, like the US Government, to issue, mandate use of, and enforce uniformity to get a large-scale adoption of a Linux operating system that has a hope of being popular enough to warrant making it as easy as Windows or macOS to use.