Once the lawyer has 5 to 7 years of experience in a certain area of law, there is not a tremendous benefit to waiting another 30 years for the lawyer to get gray. Whether you hire a law firm with 600 lawyers or with only two, only one or two lawyers will be working on your case. Before the technology age, large firms probably had some advantage because they could justify buying more books. Now that legal research is computerized, small firms have just as much access to legal resources. The one benefit with a large law firm is that they have departments in several different areas of law and sometimes, in several different regions of the state, nation, or world.
Small firms tend to be more personable and less formal.
When you talk to a lawyer in a small firm, you are probably talking to one of the decision-makers of the firm instead of one set of ears in a bureaucracy. Some people think so. Some other qualities that you might consider are hard working, prepared, diplomatic, and experienced. Lawyers with these qualities toy with obnoxious lawyers.