IMO, there is no "best" or "worst" answer to this question. The interviewer knows no one is "perfect". When I faced the question, I told truthfully "I am not 100%. If I have to answer, I don't have that many weaknesses. However, if you really want to know my weaknesses please talk to my wife, she has a long list of my weaknesses!". The person interviewing me started to laugh- and I pulled out my phone and asked her "should I call my wife?" The weird thing after the interview was that I got the job!!