I use Ashampoo Snap 6.0 which I upgraded from a free version. You can take a screen shot of an individual window, scrolling windows, freestyle, capture a video, etc. It also has plenty of editing tools. Before this, I used the Windows snipping tool.

The following reviews many of the free screen capture utilities and lists many more.
http://www.techsupportalert.com/best-free-screen-capture-utility.htm