For competition and LR shooting, my favorite FL dye is the Redding Competition "S"(bushing), if available for the cartridge. Of the three mentioned by the OP(Redding, Whidden, Forster) all are good dyes, and I wouldn't die on the hill defending one over the other, but "out of the box, the Redding Competition FL dye, has excellent interior finish, dimensional consistency(dye and bushings), and has always delivered superb overall performance and consistency with my most demanding loads, i have not had to resort to modification, or custom work with standard (SAAMI) cartridges with the Redding Competition dye to achieve Benchrest level performance.
Just my experience.