There are three important steps to follow to get a strong recommendation:

Selecting the recommender: The best recommender is a supervisor  who has interacted with you closely. Recommendations from CEOs or CFOs are absolutely useless  unless you have closely worked with them on several projects. A supervisor who can talk about your strengths, weaknesses and really knows what you are made of is one of the best choices. A peer review is sometimes sought by schools. When the recommender selection is left as an open choice, a supervisor is preferred over a peer.