A quick search also finds Hypercam and Tipcam topping the list sorted by most downloads, I notice that Cam Studio is third and the first that is totally free, althoug the other two are only $40-$50.

CamStudio is rated 5th when sorted by editors choice, in second place however is TipCam which also is free. How did make your choice for CamStudio? What did you base it on?