Barrel Length: 16" vs 18"

So, I am finally getting around to having the funds to finish my ar10 build. I am looking for some insight on choosing a barrel length.

Caliber will be 308

Gun will shot suppressed most of the time

Use: Range and Hunting

Longest range I have to shoot here is 300 yard range, so its not like I am going to be trying to reach out to 1000yds.