What is the best implant for hip replacement?

No best: There is no established best implant. There are many implants from a variety of different companies that have shown 95% excellent results lasting for 30 years or more. The question is what implant has your surgeon had the most success with? First, feel comfortable with your surgeon. Then inquire into the implants he uses, and just make sure he isn't using something for the first time on you.

Many good implants: With few exceptions, all currently available hip replacement implants have excellent track records. Many factors influence the longevity of the implant. You should seek the advice of a board certified orthopaedic surgeon who has extensive experience with hip replacements either through fellowship training or years of successful practice.