Neck sizing helps case life if your cases are failing from body splits. They usually fail from neck splits so the case life is a wash which way you go, at least with conventional neck dies,
Neck sizing may or may not help accuracy. It must be tested both ways fo learn what your rig prefers but there's rarely a lot of difference.
Lee's excellant collet neck die is perhaps the best neck die available but it has a moving part so a LOT of people seem to have trouble learning how to use it properly.