The choice of which technique to use to perform a safe circumcision is a professional decision for all Mohalim. There is no absolute best. Each Mohel has their personal favorite which is usually based on what they were taught during their medical training. The technique used is determined by the specific instrument be it the Mogen Clamp or Shield, Gomco, Plasti-Bell or other.
I personally use the Mogen Clamp (click here for example). I have, in the past, tried the other methods but for the duration of my career I have exclusively used the Mogen .
I use this instrument for several reasons. First, it is a traditional instrument, its fundamental design is based on the original circumcision instrument used for hundreds of years. The Mogen is acceptable to all branches of Jewish practice including the Orthodox. I never wanted the authenticity or traditional adherence of my ceremony challenged by any branch of Judaism. Because this technique is generally recognized as the most "Kosher", I feel secure that its use reduces the possibility of potential controversy for my work as a non-orthodox Mohel.
Second, a circumcision performed using a Mogen Clamp is more rapid than other methods. Procedure time with this instrument is approximately 30 - 60 seconds (one minute) and requires only one cut. A circumcision that takes 60 seconds seems to affect the baby less than a longer procedure. As a result of the rapidity of this procedure, I believe there is significantly less trauma to the baby.
The Gomco or Plasti-Bell instruments generally require a minimum of 5 minutes to perform a circumcision. Sometimes the procedure takes even longer. These instruments are more anatomically dependent with the need to use different sized bells for different babies. Additionally, they require the baby to be cut twice to accomplish the circumcision. Thus, I believe there is more trauma to the baby with their use.
Safety is of paramount importance with any circumcision. All instruments are equally safe in experienced hands. The difference arises with less experienced practioners. In that case a Gomco or Plasti-Bell is a bit more forgiving and allows a slightly wider margin of error for safety. I have never experienced an untoward problem with my use of a Mogen in 18 years of practice.