When we did wedding photography, I would say that 75% wanted traditional while the others wanted a mix. Funnily enough it was the older ones who wanted reportage (probably cos they already been married before) and the younger brides the more traditional.
The way we worked, we provided both anyway (my wife was the formal and I wandered around) and the traditional people tended to buy the informal ones as prints.
I prefer a mix myself rather than all of one and none of the other.