This is a common dilemma often answered by financial considerations, as bands are generally significantly more expensive than DJs. Bands can be more interactive with the crowd, but DJs have more flexibility in that they can play a wider range of music.
However, we do suggest that if you choose a DJ you ensure they are professional – not just someone’s friend who DJs occasionally. As with most things in life, you get what you pay for. There is a very significant difference between en experienced DJ and one less experienced.
If you choose a band, we strongly suggest you audition them in person. With today’s technology almost anyone could record a good quality demonstration CD. Singing and playing well live is a skill that you should witness before you commit to hiring any particular group.