I think the question is more along the lines of "What weight break cue do you want?"
There are (at least) two prevailing views:
1) 15-17 oz total weight
or
2) 21-25 oz total weight.
The "lighter is better" camp maintains that most players can accelerate a really light breaker to a higher impact speed and hence impact the cue with more speed, resulting in a harder break.
The "heavier is better" camp maintains that the heavier breaker always hits the cue ball harder, regardless of how fast the player can accelerate it, resulting in a harder break.
In either case, that weight is primarily in the butt of the cue. You should be able to use the same shaft in either.
Many/Most instructors, however, will advise you to use some backspin on the break so that your cue ball doesn't travel to the far rail of the table, but stays out in the center, more or less.
My 2 cents,
Gary