For a pretty standard mouse I always pick Microsoft mice. You really can't go wrong with them. M$ have been making some of the best general purpose mice for many years now, that are robust, nice to use, and just work. Something they are finally slowly applying to the rest of their business.

Their IntelliMouse Optical USB mice are what I use for most systems.

If you wanted the best mouse however I highly recommend the Logitech gaming mice. Specifically the G500 Gaming mouse. I use this on my main system and it is a brilliant device. It is a high end gaming mouse though so does have more buttons and features that a standard mouse, but they are useful for more than gaming. The one you might think is a gimmick is the weight system. It comes with a set of weights you can put into a tray inside the mouse, to make it heavier or lighter. I like mice to have a bit of weight to them so this is nice for me. It also has a great scroll wheel with a small button just above it. Click the button and the metal scroll wheel becomes free and you can spin it to continue scrolling until you stop it. Click the button and it locks it into a more traditional wheel you have to move to scroll. Works well. It also has a sensitivity control on the side indicated by some LEDs that is useful for different software and games.

As I said the G500 is a hardcore gaming mouse, but I didn't pick it specifically for gaming. It fits the had very nicely and the features are all useful. But if you don't want all that then the Microsoft mice are worth it.