OOOOOOO, nice pretty colors on the butt plate!  :o  I'm going to have to try that!

Rust bluing is by far my favorite.  I think it imparts a rich, dark, deep blue and, I agree, is the more durable finish.

Cold bluing gets laughed at but you still can get good results.  I use it a lot on small parts and touch-ups.

Plum Brown works great for getting something to look old with a nice even, kinda mottled brown patina. Like an old musket barrel or socket bayonet.  Actually, I get confused sometimes because the word browning is also used to describe the brown finish applied to really old firearms.