They are both very committed and driven people. They both may be on the Autistic Spectrum, Musk admittedly and Stallman maybe though some say no. They both are influential. I would find it hard to choose. Free Software is in everything. Stallman is older so the majority of his work is in the past, Musk is just passing his prime. Musk is good at making money which is his benefit not ours ... and hitching is name to other people's companies and work. His own... Spacex maybe... not sure about the otgers. In terms of accomplishment a lot of both is the result of other peoples money and work... but that is the nature of things. There are other similarities...