Butter gives puff pastry its signature flavor and flaky texture. Brands that use shortening instead of butter tend to lack the taste and appearance of true puff pastry.
The use of butter is essential to its flaky layers, and other fat substitutes just won't deliver the same kind of boldness that you're looking for from a puff pastry.
The ideal dough will use butter with higher fat content, such as those labeled "European" butter. More fat means that your pastry will be more flavorful and texturally pleasant.