It seems that DJ's are last in line. Many brides start with choosing a nice venue, move to the food, the flowers, the photographer, and leave little budget for the entertainment. Hopefully these stats will shine some light on what's most important and most memorable:

72% of all brides say they would have spent more time choosing their reception entertainment.
Almost 100% say they would have spent more of their budget on the entertainment.
Within one week after their reception, 78% of brides say they would have made the entertainment their highest priority!
When asked 81% of guests say the thing they remember most about a wedding is the entertainment.