A very good point is made here by David Levine, Americas head of litigation and regulatory enforcement at Deutsche Bank.

When working as an in-house lawyer I've held quite a few "beauty parades" where BigLaw firms have given presentations and pitched for business. It's surprisingly common that a firm cannot answer the question why we should have used them rather than another firm. Law firms do need to get this right!

I'll give these small tips though - I've always ended up appointing the firm that gave the most passionate and most enthusiastic pitch, that seemed hungriest for the work and whose people came across as the ones we'd most enjoy working with.