meteor22 wrote:
I sit at around 50 centimeters or less.
The closest the better because the light will take less time traveling from the screen to your eyes, so less input lag 
I think the "input lag" for light travel would be around a fraction of a nanosecond.
To add onto the topic, what really matters is the scale. Most methods of play (mouse, tablet) require muscle memory independent of the viewing distance because the muscle movements always correspond to the scale onscreen, rather than the scale presented visually. Generally speaking, your mind can negate most common viewing fluctuations but 1-2 meters is a rather large change (I assume that was just an example number though). If you can see the entire playfield without straining your eyes or your neck, then you're in an acceptable viewing distance.
I find that being closer to the screen allows me to be more precise with my cursor movements but being further allows me to foresee patterns and make long jumps easier. However, my playing method is highly dependent on viewing distance and screen scale, unlike mouse/tablet, so I can't really project my experience onto another player.
