When I look at a Linux board I look at hardware/software/documentation/price I have yet to see one that combines those 4 criteria better than the RPI.
Yes, there are plenty of other boards out there, some more powerful than the RPI. But, in my opinion, nothing come close to the above mentioned criteria.
Yes RPi has "better" (more widely available works be a better term) software support, but there are certain things that you should consider.
For instance they insist on using propietary hardware work closed source blobs. Whatever you install on your RPi does not directly control the hardware, as there's already an OS in between (the RPi "firmware").
The Raspberry Foundation has never developed anything and has never contributed anything to the open source community. They are supposed to be a non-prifit, but I bet they've made a ton of money. They do unfair competition as they don't pay any taxes (because they are a "non-profit for education") do their costs are lower and they can sell all lower prices.
Just search why Armbian does not support RPi and you'll learn a lot of things about this "Foundation".