Interestingly, Valve boss Gabe Newell doesn’t use WASD. “I personally don't like WASD as it takes your hand away from your typing home keys,” he wrote in an email to PC Gamer. “I always rebind to ESDF.” Newell's not alone there. Do a little Googling and you'll find plenty of people arguing that ESDF is the more natural configuration.
More surprisingly, another Half-Life developer, level designer Dario Casali, also rejects WASD. Instead, he prefers ASXC. “It feels natural to me, where WASD feels odd,” wrote Casali. “But lots of people scoff at my config.”