When it comes to choosing a photographer, its important to choose someone who is showing work that you would be happy to receive yourself.
Photographers are careful about the work they choose to show in albums and on websites. Its chosen to show off their style at its best, and to attract clients that want that style.
However brilliant a photographer is at shooting traditional, formally posed photographs, it doesn't mean that you can ask them to shoot photojournalism and expect the same level of quality. And the reverse applies too - photojournalists call themselves that because that's what they're good at. And if you're looking for a contemporary, editorial fashion style of photography then again, make sure that's what the photographer is showing as their best work.
You know the saying "Jack of all trades, master of none" - really good photographers tend to be really good at specific things.
It doesn't mean that a photojournalist can't shoot group photos or that traditional photographers can't shoot candid photos. They just won't be as good at it as a specialist.
I specialise in photojournalism because its what I'm good at. The work I show on my website and in my sample albums is photojournalism and clients come to me because that's the way they want their wedding photographed.