2. Gameplay
It should always be the most important factor. Gameplay matters way more than graphics. Just as well the PC does both better than anyone else. Just look at the range of games that defined the PC: War-strategy deployments, management-sims, virtual-people, shoot 'em ups, point-and-clicks, keyboard-instruction-based-games, racing-games, RPG, MMORPGs, puzzle games... the list goes on. The PC has always offered a more broad range of games, and more technical gameplay than its competing consoles.