Big 4 accounting firm

PwC is the biggest...

Pwc: lot of reputed and large client like: TVB, American Express, Bank of china and Espirt…
KP: many financial institutional clients, solid training
deloitte: lots of client, friendly
EY: Putting Our People First

As you are a new graduate, I don't think it makes quite a difference for you to join any of the 4 firms. The distinct features of each well-known firm are not so critical for making your decision. Rather, it is you yourself how to plan your career path and your willingness and endurance to learn during your stay in the Firm.