Is social engineering better than man in the middle attack to get passwords?

Yes social engineer is the better approach                    

yes absolutly kali linux or backtrak are the best systems the hacking and get passwords

Yes, Social Engineering is better than Man in the middle Attack especially you need precision of information in a limited time. 

Yes Social Engineering is Better in a lot of situation But Both Are effective based on the situation you're facing .

Yes in my opinion Social Engineering is better approach because these days traffic is encrypted so MIT is not as effective as Social Engineering. You can social Engineer the target to get better results