rickyp,
The best barrel is the one that shoots best for you - there are many national, international and local barrel makers and I would suggest that you talk to a few of your local smiths to find out who they like to use and what they use them for.
The break, or anything else that you hang on the end of a barrel, will affect the barrel harmonics but it is impossible to tell in what way.
The 21 inch barrel is short for the three rounds that you name but if you are carrying it in the woods then the short barrel might be easier to move through the brush.
It all depends what you are going to be doing with it.
PaulS
