WASD for me.
I'm old enough to have been around for the advent of FPS games and I've used arrow keys for a long time. In fact, I've spent years keyboard turning in FPS games (no mouse). Yes kids, once upon a time that was quite viable, at least in single player. I was young and foolish...
The whole thing changed when I came to one of my first LAN parties and sat down to play Quake 2. One of the older players saw me with both hands on the keyboard, got up, came over and didn't leave until I accepted to play with a mouse. At first, circle strafing, mouse aiming and using letters instead of arrows was a cultural shock to me, but I rolled with it since I was suddenly able to hit a moving target. Fast forward a decade, and I'm a die-hard WASD user, as it should be
ESDF is also viable (and arguably superior), but I'm a traditionalist and stick to WASD.