While there are a lot of CPUs on the market, there is certainly a group that is the cream of the crop. For Windows users, the best CPUs are Intel i5 and Intel i7. These CPUs get great reviews and can handle anything you throw at it.
Personally, I highly recommend the i5 series of CPU. They can handle just about anything you throw at it and will keep your computer running extremely fast.
If you do video or music editing, you should consider upgrading to i7. As of right now, Intel i7 is considered the top of the line CPU on the market for most personal computer users.