Most comments here seem to be remembering him for his philanthropy and contributions to science and humanity, rather than for being a co-founder of Microsoft.
It's an interesting contrast to the thread from 7 years ago about the death of Steve Jobs [1]. Steve Jobs was a visionary, but he wasn't a philanthropist. His legacy is Apple, Allen's legacy is his contributions to charity. Gates will be the same, he will be remembered as the man who tried to eradicate malaria, not the man who made Microsoft Windows.