Suppose you only have one yeast available to produce wine, beer, liquor from fruits or grains. say post apocalyptic future, and you manage to have fruits or grains and you want to produce alcoholic beverages by manipulating fermentation. What kind of yeast you will keep? (do not take into account the natural process (for instance, yeast in the skin of grape), the idea is that you want to accelerate or enhance fermentation)
Being very much biased toward beer, I suggest White Labs: Cry Havoc as it will ferment at both ale and lager temperatures.
Arguably, in a post apocalyptic scenario won't have the electricity to cool any wort/must to lager temperatures but I would be able to find a northern climate that would be more hospitable to lagers.
All that being said, the idea that anyone would be able to keep a pure strain in less than laboratory conditions is laughable. Any fermentation would quickly lead to a hybrid that would thrive in the current (less than ideal) conditions that persist.
Champagne yeast is the king of yeasts, it will ferment anything, and it will tolerate higher than usual alcohol levels for those who wish it.
When other yeasts have failed, it is often a yeast tossed in to save a batch.
It's only downfall is that it is not a gentle yeast, and does not ferment slowly. You therefore can lose some of the more delicate aromas and esters.