Again, has been mentioned quite some time back. There isn't any best mouse in the world. It doesn't mean that the more expensive the mouse is, the better the mouse is. And same goes to the dpi/cpi or whatever you named it. Doesn't mean the higher the dpi/cpi of the mouse, the better the mouse.

Most important thing when you buy a mouse, especially 'gaming mouse' is the comfortableness of the mouse. Meaning, you feel comfortable using the mouse for long hours. 5 hours for instance? Or few hours. Then only you look at the specification of the mouse. What type of games you play for example. If you are playing FPS which doesn't need 10 buttons, then no point getting a mouse with 10 buttons. Like wise, if you are playing rpg,rts or any strategy games that requires some macros. Then maybe you will need the buttons for macros.
Anyway, is just my 2 cents for forumers/gamers/anyone that has been asking what mouse is the best. Cause different people has different needs. But there are few good mouse around the market depending on budget. =)