I want to buy the type of bread which last longest. It should be toastable, so no zwieback and other dry types. Which is the best bread for this purpose? Is the standard toast slices or loaf of bread better?
Much of it has to do with how you store it, and what the issues are in your area with that storage method in the given season (is it going to go stale before it goes moldy?)
I find that the bread that's least likely to go off before I get to the end of the loaf is sourdough ... but I get my sourdough from a place that uses a real starter, and isn't just mass produced with a sour flavor added.
... but there are also breads with additives & preservatives in them that they'll easily resist molding for more than a week ... but it doesn't make particularly good toast in my opinion.