If you are going for pure reportage/pj, then the relationship with the photographer is not really relevant as you will have no interaction in the day with the photographer (apart from 6-8 group shots...possibly).
In this instance, I would go for quality of photography over personality....
That said, many people are after a mixture of relaxed style photography with the dynamic of what they want structurally from their day....specifically family and friends shots. In this case, it is more important that the photographer has a style and attitude that gets on well with the couple, the parents, relations and the friends.
There can also be "issues" with the style of photography where the couple want one style, although the parents may be paying for the coverage and expect something different and more traditional. This is where experience in the business comes to the fore to ensure that all sides get what they want....
Peter