agree with Gene, but also five tenths difference at best.
Here's why:
* your probably using a standard factory chamber in something or another. If not I'll expand later. I've probably said that neck sizing, and turning necks as well is almost a waste of energy with a factory chamber. I've seen a couple rifles in the past that it helped a little bit, but nothing huge. Still five tenths here and three tenths there start to add up into serious numbers.
Now here's what I'd do. First of all I'd but a good strait press, and this (in my eyes) leaves one with two choices. The Co-Ax and a distant Lee cast iron press. The Forster is well known to be arrow strait out of the box, and the Lee seems to be straighter than most all the others. Also depends on how much cash you have on hand. Dies for these presses are simple. You order in a set of Forster .308 national match dies (they are a standard catalog item by the way).
Now if by some slim chance you have a custom barrel and chamber, you might want to think about the Wilson die. It has it's draw backs, as well as pluses. You'll still need a good body die or full length die to reset the shoulders every now and then. The Forster seater is the best in a threaded die period. Still it can be made better! I recommend ordering in a 7-08 seater sleeve from Forster, and reaming the neck to about one thousandth larger than your cases when loaded (five tenths if your brave). You'll be removing about .025"/.028" from the neck I'd. That way the neck of the case will fit the die far better. Or you can simply use a Wilson inline die and a good arbor press. I use a K&M for neck sizing and bullet seating. Still you can't bump shoulders or full length size with the arbor press. There's still another option here, and that is to buy a blank and have it reamed to fit the chamber.
In the end you'll get your straightest ammunition with the Forster press and national match die set, unless you opt for the Wilson.
gary