There was also "Coltguard", which was, as I recall, just an in-house name for electroless nickle. It was only listed for a short time.
Stainless is, of course, the most durable, blue the least.
Bright nickle is probably less durable than the electroless finishes, since the bright nickle gun is first plated with copper, than over plated with bright nickle. This "layered" finish can crack, peel, and chip. Also moisture can work it's way underneath the plating and cause rust.
Electroless nickle is applied directly to the base steel and doesn't have these faults. The electroless nickle material itself, is the most rust resistant of all, as long as the integrity of the coating isn't broken. If scratched through, the exposed carbon steel will rust quickly.
Of the bright finishes, stainless will probably scratch the easiest, BUT is also the easiest to repair. A grocery store green synthetic "scratch" pad will restore the finish.
The nickle finishes have a "yellow" cast to the plating, while the stainless has a true "white' color.
Being a very hard, "Slick" finish, the electroless and bright nickle finishes are a little easier to clean, since fouling doesn't stick to the finish. Stainless is very easy to keep clean, since you can use a "lead removal" cloth to clean carbon off the cylinder face, and you don't have to worry about damaging a finish coat. These cloths will remove the bluing from a blued gun instantly.
Nickle finishes can be damaged by powder solvents, if the solvent is left on too long.
