Hey
I would think that many firms deliver premium legal services on challenging matters whilst providing sound business judgment. Why would clients pick
Dechert over any other firm with a similar profile?
I would have a look on their website firstly to see what they appear to be proud of in terms of the service they provide to clients. For example, some firms will talk a lot about their client centric or innovative approach (this is just an example, you would need to be more specific than simply saying they are 'innovative').
Once you have worked out how they entice clients to instruct them, and how this benefits the client, you should then have a good foundation to build upon with further research.
Hope that helps!