Many will say cost, but there are DJs that cost as much as a band. The question you and your fiance have to ask yourselves is: What type of music do you want at your wedding?
A wedding band will play a wide range of songs and can get your guests moving but the songs won’t sound exactly like the original artist. A DJ can play a wider range of songs, can get the crowd moving and their music will be the original recordings.
You can also hire the reception band or DJ to play music during the ceremony and cocktail hour, making it one entertainment company you are working with.
And while I’m not making the case for either one as detailed as a wedding band musician or DJ would, the simple question is what do you want to hear -- the exact song by your favorite artist or can you live with a cover of it?
I’ve been to weddings that had a band and weddings with a DJ and both were great parties. Do your research and try and see the musicians/DJ perform live if possible to get a feel for their sound, energy and how the crowd reacts to them. If the audience is having a great time then your guests will probably enjoy them too.