"Best" can be a relative term. From
https://www.pegym.com/forums/penis-...ts-opposed-jelqing-exclusively.html#post36835 :
There are pros and cons to each method. Here are some advantages and disadvantages to the various methods:
Extenders-
Pros:
-You know exactly how much tension is being generated
-Workout is "hands free"
-Progress is easy to track and forecast
-Can be worn with certain clothes
Cons:
-Requires constant supervision
-Maximum tension possible is very light
-Must be worn for many total hours to see results
-Can be uncomfortable without adequate padding
Weight hangers-
Pros:
-Workout is "hands free"
-Very high tension is possible
-You know exactly how much tension is being generated
Cons:
-Injuries more common with this method
-Often uncomfortable even with adequate padding
-Cannot be done in public
Manual exercises-
Pros:
-Very convenient
-Very high tension is possible
-Tension level is easily adjustable
-The most fluid of all methods
Cons:
-Tension is difficult to measure- must use estimates
-Cannot be done in public
-Must have relatively strong hands for hard or long workouts
Please feel free to add to this list
My personal preferences favor manual exercises, although each method is effective when done correctly.