I have and use all of the above in different calibers and guns here. In my opinion the "S" dies that require a bushing appropriately sized for your application are probably more than you want to get into initially. I use them on a few of my target only and benchrest guns, and I personally use them only on ammo that I turn the necks on. As far as the competition dies, they are nice with the mic on the seating die and probably better tolerances. My experience is that the regular die sets from Redding, used correctly, will make very precise ammo and are all you need for most applications. As far as neck vs full length, I usually have both. I use neck sizing whenever I can until the shoulder of the case needs pushed back a little, then use the full length for that. With some guns/loads it is every 2-3 firings, on some it is more than that. Remember, brass sized with a neck size die must normally be shot in the same gun, as the rest of the case is fire formed exactly to the chamber it was originally fired in and it may not chamber in another gun. Hope this is helpful.