Work-ex is definitely preferred before a MBA. MBA will make much more sense to the candidate if he has had exp of working in a firm before.It will be easy for him to relate to the concepts taught in class.From the employer's point of view,an experienced MBA is better as he can start delivering from the day 0 and will be much more sensitised soul than a fresher.Its important to remember that organisations are made up of people and outputs are a function of people who work there.