There were better contemporary mathematicians than John Conway, and there were (a handful of) better contemporary popularizers of mathematics, but no one else came close to doing both nearly as well.
I met him on a few different occasions when I was very young (middle and high school), and he was always extremely generous with his time, especially with an interlocutor not legally old enough to drink, and clearly brilliant in person. One example of his generosity was his collaboration on a book about triangle centers[0] with the late Steve Sigur, who was not a research mathematician but a high school teacher.
Of course the Game of Life is an enduring classic, but I’ll also always have fond memories of Winning Ways for Your Mathematical Plays and Sphere Packings, Lattices and Groups (affectionately known as SPLAG). The mathematical world has truly lost a living legend.
[0] https://books.google.com/books/about/The_Triangle_Book.html?...