I assume were talking 700 clones, if your looking to squeeze the every last bit of accuracy out of the rifle than I think a custom action will get you there, scope base holes that are inline with the centerline of the bore and most use the 8-40's which are stronger than factory,
Some have a better fire control systems with a guided firing pin that when you squeeze the trigger the FP doesn't bounce around behind the bolt face trying to find the hole, this can lead to unexplained flyers as the actions vibrations are not consistant shot to shot,
Some of the better customs are finished machined after heat treat so the action bodies are usally straighter with exceptional tolerances which leads to better accuracy!
Better bolt timing and extraction surfaces..
Some people like the looks
Some like how smooth they feel over a Rem 700
But a 700 with a little work can still be a very accurate hunting rifle!
