Arrow keys whenever possible. Gives me quick access to 30 keys, assuming the game in question recognizes keypad strokes, ctrl and shift strokes as individual keys.
Also, my right hand is on the mouse, I just slide my keyboard over... my keyboard occupies a cleared space that's about twice its width.
**edit** justification: I demand absolute precision. W in WASD is not up, it's up-left. Hence, when using WASD, I often hit W and E simultaneously when attempting to hit up. Letter keys are not designed for gaming on most keyboards. Arrow keys always were.
Plus, realistically with WASD, one has access to maybe 20 keys with their left hand... and that's with quite a bit of stretching.