Be more specific !
What is most important... Its a compromise weight is a factor !
24" Bull barrel will give you accuracy and distance. If that is the case , then... Get a Dpms 24" Bull barrel that Brownell sells for a little over $900 . but that combo is heavy. If you want light then get a 14.5" pencil barrel with an attached brake but you give up accuracy. So that leaves 18" to 20" medium profile barrel which every body likes, but it compromises speed and accuracy and weight. This is the combo is what most people will lean toward. Every manufacturer has one. So pick a type first.