This is actually a good debate. Always a trade off.

Shorter barrel = stiffer barrel and less whip. Also lighter to carry.

Longer barrel = generally, more muzzle velocity. Increase/decrease depends on caliber, bullet weight, and powder used.

Built a 32" barrelled Savage in 338 RUM that is an absolute tack driver, especially at long distance. Have personally witnessed a 20" barrelled 223 shoot lights out at 600 yards (as in, under 2" groups).

Decide what YOU want to build and go from there. Nice thing about Savage rifles...you, a barrel nut wrench, and 15 minutes of time equals a barrel change.