What Makes A Federal Criminal Lawyer More Successful Than The Others?

We are aware, there are thousands of Federal criminal lawyers, practicing criminal cases day in and day out, across all states of America. All of these criminal attorneys are professionally qualified and possess good knowledge of criminal law, across the States. However, then what is it that makes some of them stand out of the crowd and demand higher fee than others? Why are people still hiring them even though they are costlier than the others?