The best camera for benchmark hunting is generally the smallest camera. Lots of megapixels are not necessary. The most important feature of a camera for benchmark hunting is the ability to take a closeup shot of a benchmark disk so that it will mostly fill the screen. This usually requires the camera being able to focus from about 4 to 6 inches from the benchmark. This usually involves a macro-setting on digital cameras.
If you cannot focus that close, and your camera has lots of megapixels, then pick the distance that looks clearest and use photo editing software to crop the image.
Read the section on disk cleaning. Also note that cornstarch or other powders can make the lettering stand out and greatly improve the readability of the disk in your picture.