When a plank is quarter sawn vs flat sawn it becomes twice as dimensionally stable, ie it contracts or expands half as much with change in humidity. An 8” plank of quarter sawn will have the same stability as a 4” flat sawn. If you are looking for an exceptionally wide plank floor but want to minimize seems this is an option.
As for appearance, the quarter sawn plank will have a very pleasant vertical grain look. In some species (white oak in particular) the appearance of flecks on the plank adds to the unique and preferred appearance.
Quarter sawing is typically time consuming and not an efficient way to saw therefore the cost of the finished floor is more expensive.