If you're indoors, any of the Primesense devices are best (Kinect or Asus Xtion). If you're outdoors, you can't really rely on the Kinect -- the projected IR l

If you're indoors, any of the Primesense devices are best (Kinect or Asus Xtion). If you're outdoors, you can't really rely on the Kinect -- the projected IR light patterns get drowned out by the sun. Then you have to go a time-of-flight solution: the Swiss Ranger SR4000 (expensive!) or the PMD Technologies sensor (I've heard they're available for a couple $hundred now). Kinect2 is supposed to be time-of-flight when it is released too.