It all depends on how much you want to spend and the conditions of use.
Logitech and Microsoft both have a good range availble. The logitech cams are good from what I have heard but the drivers and software are not the best. The line of Cams from Microsoft are not only of good quality but they have many to suit different needs and prices. Microsoft's top of the line cam the Microsoft LifeCam VX-6000 which retails around $130-$150 and is the one I just I just recently purchased and I am quite happy with it, the image is good and the inbuilt mic performs nicely.
The cam has a wide angle lens and the ability to zoom and to move the camera to a degree using the software.
The software driver package 'microsoft lifecam' weighs in at a huge 160MB and is just a basic program that makes the cam work.
To gain the best of your cam the free app
http://www.superwebcam.com/ is the way to go and it is free. The app
http://www.webcammax.com/ is another excellent program but is not free, tho it is only 30us.
What ever cam you decide to buy if you spend close to $100 you should not have any problems.