Which is best to use when selecting a clustering procedure: hierarchical or nonhierarchical clustering?

What will be an ideal response?

Although nonhierarchical clustering is faster than hierarchical methods and has merit when the number of objects or observations is large, it has been suggested that the hierarchical and nonhierarchical methods be used in tandem. First, an initial clustering solution is obtained using a hierarchical procedure, such as average linkage or Ward's. The number of clusters and cluster centroids so obtained are used as inputs to the optimizing partitioning method.