There are often certain features of one manufacturer's dies that make them more desireable than the dies of another. But as far as the quality of the ammunition which they produce, it is my opinion that you will not be able to tell the difference... until you get into neck turning and all of that.
Ferinstance, I like the Lee seating die that you can set seating depth with thumb and forefinger, rather than resorting to a screwdriver and a wrench as on the RCBS. I think that the RCBS sizing dies are a little "slicker" than the Lees, and offer less resistance to sizing. The Redding die is comparable to the RCBS in every way, unless you factor in the micrometer seating die. If the prices were the same, I wouldn't have a preference. That the RCBS is $15 less, I would buy those dies.