3D Sensors are used for many different applications, e.g. scene reconstruction, object detection and mobile robots, etc. Several studies on usability and accuracy have been done for different sensors. However, all these studies have used different settings for the different sensors. For this reason we compare five 3D sensors, including the structured light sensors Microsoft Kinect and ASUS Xtion Pro Live and the time of flight sensors Fotonic E70P, IFM O3D200 and Nippon Signal FX6, using the same settings. The sensor noise, absolute error and point detection rates are compared for different depth values, environmental illumination and different surfaces. Also simple models of the noise depending on the measured depth are proposed. It is found that the structured light sensors are very accurate for close ranges. The time of flight sensors have more noise, but the noise does not increase as strongly with the measured distance. Further, it is found that these sensors can be used for outdoor applications.