depending on your career plan. If you love doing research and would like to take it as your career, apply for PHD. Otherwise, master degree is enough. It's not worthy living in the tough PHD program.
@July, thx so much for ur prompt reply.Honeslty, I am a bit confused,say, for example, how did you properly target the right program which may fit ur aspiration as well as ur capability.
If you do not mind, can I please also know where do your guys find your professors whose research area appeals to u? I am not very good at it and your advice is highly appreciated. Thanks!