Asking which mouse to get is like asking if ATI or Nvidia is better. The optical fanboys will come knocking if they are down wind.
As long as you get a recent laser mouse, I would say pick the mouse that feels the best in your hand and has buttons where you want them over anything else. I owned a G5 for years and currently own a G500. I can shake this thing back and forth as fast as I can on a budget pad and don't notice any loss of precision. The laser sensors are good enough now that I wouldn't worry about that being a deciding factor.
The button placement is where it's at for me. Back and forward buttons on the side, which are useful for both web browsing and gaming, plus a center button to assign to whatever else. And the toggle switch to make the wheel spin freely is kind of neat too, though I don't really find myself using it much.
One thing I don't like about it that I also didn't care for in the G5 is the left and right toggle on the wheel. It can make pressing the center button a bit awkward, but I will admit it is better than it was on the G5.
While laser sensors are superior at tracking on multiple surfaces and at higher DPI, it surely doesn't mean the sensor is "better" Both laser and optical have their share of problems.
In the end, it's all personal preference. I cannot emphasize this enough
Edited by Skylit - 1/10/12 at 1:55am