I have bought a few neck sizers and they are ok. But sometimes they crook the necks and you get bullet runout. So I dont' buy the RCBS necksizer anymore but usually buy the collet die from Lee. Redding competition also makes some very nice neck sizers that support the brass to make sure your necks are not crooked but very expensive.

Only down side of the lee, is I have usually polish the collet to get correct neck tension and smoothness.