Is it best to resize just the neck or the whole case?

Neck sizing usually gives better accuracy and case life. Even if you neck size, often cases may need to be full length sized ever 5th or so firing, depending on the load intensity, etc.

For hunting purposes, a full length size or partial full length size is my preference, just because they chamber a bit smoother. Incidentally, I've had very good accuracy results with partial full length sizing.

good luck

What do you intend to do with the loaded round?

For hunting, where feed & function matter, full length resize.

For targets or varmints, where it's single load & top accuracy matters, neck sizing often yields better results.

For an autoloader (or pump or lever action as well), full length size for sure.

Give us a little more info... caliber, rifle, intended use, etc, and I'm sure you'll get some good answers.

I routinely neck size and would have no qualms about hunting with those loads, but you should cycle any loads you're going to hunt with through the rifle to make sure they chamber and extract easily. Neck sizing is unlikely to work if you're loading ammo to be used in more than one rifle, too. The reason it MAY improve accuracy is that each case is perfectly fireformed to the chamber it's being fired in, reducing the cartridge's freedom to move out of alignment with the bore. But production tolerances between different chambers may mean the case fired in one rifle will jam in another.

I full length resize all my dangerous game reloads, and my lever action cartridges...and neck size hunting rounds to one degree or another or have off and on for years...

For positive feed and function, full length is the best route....and they shoot just as good for hunting purposes. The longer I live the more I just full length resize, it simplifies my life and I trade guns a lot soooo....

I have seen little practical difference in accuracy and I see every year someone in camp that has oversize ammo that won't chamber or sticks a bullet, and I had 4 rounds last year that would not fit my double as I had changed guns, fortunatly we discovered it before things went south with a buffalo....

Its easy to claim you test every round before you hunt, but thats BS, sooner or later you will drop the ball and skip that function and ooooops!