Some people argue that every keyboard is a great peripheral for gaming. While that might be true, some keyboards are simply better for gaming than others. The same is true about mouses. I think that the middle button is very useful in many situations, and I know that some of the mouses do not have one. From my experience, I can say that a laser mouse can be better for gaming as they are very reliable. If you use a roller ball mouse, it might stop working at any moment due to dirt being accumulated. It might happen when it could be a disaster for it to stop working, like during a tournament. Many gamers use mouse of reputable companies like Logitech or Microsoft, and are very happy with their precision and overall performance. Do not forget to make sure you have a reliable mouse pad as well. A high quality mouse pad will ensure that your gaming experience will be more enjoyable.
Of course, it all depends on what kind of gamers you are playing. First Person Shooters require a very precise mouse, while almost any mouse will be suitable for role-playing games. Some gamers spend a lot of money on various peripherals, but before you do so, I suggest that you make sure you really need them. Most gamers will not need to buy expensive peripherals. Make sure that you are not buying some expensive mouse or keyboard only to show off.