What matters more for pixel-level cursor accuracy: the mouse pad or the sensor firmware?

Sensor firmware matters more. The pad affects feel—cloth gives friction for micro-adjustments, hard pads can make the cursor skate too much—but if the firmware is garbage, you’re fighting the mouse. Modern optical sensors handle almost any surface well enough; firmware controls lift-off distance, angle snapping (keep it off), and motion smoothing. For pixel-level work, choose a mouse with zero angle snapping and low lift-off distance, paired with a medium-friction cloth pad like a Steelseries QcK or HyperX Fury S.