I don't agree with this sentiment .. I think this is a very shallow approach to evaluating people on the basis of their past accomplishments, and also somewhat presumptuous to consider that they might 'outdo' their past accomplishments just by working for you. Therefore in my opinon the most important interview question to ask is this:

"Do you want to work here?"

.. followed up by:

"Why do you want to work here?"

If the answers to these two questions don't jive with what you need/want as an employer, then there are no further questions to ask.