1. How reliable are the rankings by the following: Benchmark Litigation, Legal 500, Chambers, Forbes etc.

2. What are their criteria for assessment & ranking and should one apply only to the ranked firms for internships and jobs?

3. What are other ways to know which firms are doing good work in the particular practice area?

They are kind of accurate but its better to look up the partners and dig further deeper into the deal announcements of those particular law firms.