I use the for my auto pistol reloads because they make them work in my assortment of pistols.
But I also like them because of the way they adjust the crimp and the 4 die Lee set has a better price than most 3 die sets. I also want the Lee powder/expander die. All the same is true for my revolver loads but the carbide ring does nothing in those on my reloads but the 4 die set is still a good buy particularly if you use the Lee PM and want the bullet seating die and crimp die that does not need lock rings to adjust. They just have features that I like. Just personal preference .
If I have a situation where I need a different die if I don't already have one I will get it.