I don't recall ever seeing any factory revolver ammo that wasn't roll crimped.

You will find many internet forum members who say they taper crimp theirs, but they are usually talking about light target loads. Rolled crimps serve to keep the bullets from being pulled out of the cases from recoil and to help slower burning powders burn more efficiently and uniformly. They also help keep the bullet from being seated deeper in case the cartridge is dropped.

For the most uniformity using roll crimping, the brass should all be the same length. Those that taper crimp do so to keep from having to trim their brass, which most people don't do anyway for handguns.