There is a very good feature comparison on dpReview site
To give you some summary:
In terms of picture quality I would say that you would not spot a difference between results achieved from all the camera on the list, and I would say that the choice would be more related to handling and the way you are planning to use the camera.
7D is pro grade body, with magnesium body and environmental sealing. It has an excellent pro grade autofocus and offers 100% view viewfinder. So it will have an edge when it come to shooting sports, birds and in rough conditions. Those features come at price though.
50D has pretty similar body to 7D (magnesium) but it is not that well sealed and the autofocus is a bit lower quality as well.
60D has plastic body, same autofocus as 50D and similar sensor to 7D. It offers swivel LCD which can come handy in some situation, and its lower weight and size can be considered an advantage by some (me included).
So you need to handle the cameras, consider your budget a see which one works best for you.