How do the various methods of roasting beef compare?
A roast is a roast is a roast.

Roasting is a method of cooking that involves the aplication of a lot of dry heat to a peice of meat. You can obtain a great roast from all the above the cooking methods as long as you take into account the various ways they work.

A rotisserie offers all around even heat and will remain juicy although you can lose some juice from the skewer through the center, but may not cook the roast as perfectly as you lack good tempature control.

The oven is a great way to roast meat as long as you use the two tempature method.  That means you start high and finish low or vice versa.  I tend to side with Alton Brown on this and start low (normally 200 but you can adjust according to time requirements) until my roast is ~25-to-20 degrees of medium rare, pull it out and bring the oven to 450, put back in and remove to rest at 15 degrees short of desired doneness.  You also have to make sure that you raise the roast off the bottom of the pan because if you don't you will end up braising the roast in it's own juices.

Your grill can work as long as you keep the lid closed and the roast from directly over the coals, but it is going to be the method that needs the most constant attention and will be easy to end up with a overdone outside and a underdone interior.