I think that most of us have a strong preference for some food brands because no one else makes that food taste as good. For example, I rarely buy any cola drink but coke because it has a citrusy brightness which the other colas lack.
Similarly, I prefer Heinz ketchup because it has the best balance of sweetness and acid (vinegar).
My last one is A-1 sauce. I think it has a "raisiny" and anchovy taste that other steak sauces lack.
What surprises me is that in this age of spectrometers, you would think that competitors, having had their brains beaten out in the market place, would try to make their products virtual duplicates of the winning brands. But they don't.
Do you buy certain foods because only that one manufacturer makes them taste that unique way? What are they? And why do you prefer them?