The Pixart PAW 3950 beats the older PAW 3395 both on paper and in the smaller areas you might notice it working away. However, I'd recommend against buying a gaming mouse purely for its sensor alone.

Ever wonder who will be responsible for the motion sensing part of Nintendo's motion-sensing Wii remote? PixArt Imaging Corporation, "a market leader in CMOS sensor SoC (System-On-a-Chip) and ...

The PixArt PAW 3335 is a great mid-range sensor and is found in both XPG Alpha mice. The wireless dongle is actually stored inside the mouse itself.