Yeast is a major key in differentiating a good wine and a truly great, award-winning wine.
I experiment a fair amount with different strains of yeast and over the years I have narrowed my wine production to the following strains:
A good all around yeast, especially with wines with low pH or starting the ferment at low temperatures. If you need the fruit wine to ferment to a very dry level, or to make a sparkling wine, this is the yeast to use.