Thank you for the comments so far. Based on the research I have done on other forums the opinions are:
Phosphate - rougher finish soaks up and holds oil better. The rails will polished over several thousand rounds becoming very slick. The rails can be polished manually to speed up the process.
Black Nitride - smooth slick surface.
NiB - smooth slick plating that easily cleans up.
The biggest disadvantage with the B.N. and NiB is that do to being slick they do not hold oil well to their surface. I have not found much actual claims of NiB chipping.
Sometimes you have to think about the information that is posted on the internet.
# Phosphate = Rougher finish. Will hold oil better because, it needs to. Other then oil getting into the pores in the surface of the metal, metal does not soak up oil. Phosphate BCG's tend to need more oil, they like to be wet. When the Phosphate finish rubs off, you have bare metal.
# Black Nitride - smooth slick surface. Also a harder surface. It's a metal treatment. The black color is a result of the process left on the surface. When the black wears off, you still have treated metal.
# The biggest disadvantage with the B.N. and NiB is that do to being slick they do not hold oil well to their surface. You can run a Nitride or NIB BCG wet just like any other BCG, they just don't need as much oil due to their smoother finish.
I have bought several brands of BCG's. The first Niteide BCG I used was from Crosshill Technology. I believed they were bought up by OMEGA Manufacturing which is the Wholesale side of Delta Team Tactical. DTT is also the distributor of Davidson Defense. I have also used the Davidson Defense Nitride BCG's. Both of these BCG have been very slick with the metal finish being very smooth.
https://www.deltateamtactical.com/Bolt_c_109.html
I have an Odin Works Nitride BCG in one of my rifles. It is the slickest Nitride BCG I have.
I bought BCG's from Surplus Ammo. I believe they buy their BCG's from Tool Craft. If your looking for that BCG that's a little different, check them out.
http://www.surplusammo.com/categories/ar-15-parts/bolt-carrier-groups.html
The only BCG that I don't care for are from Radical Firearms. My buddy bought one of their complete rifles about two years ago and it just would cycle. I checked out the rifle and the BCG just didn't look well made. I had an extra Davidson Defense Nitride BCG so we put it in his rifle and it worked perfect. Radical Firearms states that they make all their rifle parts in house. They may have gotten better at making BCG's by now, but I'm not sure.
Now Brownell's has a lot of BCG's and give you a lifetime warranty on anything you buy from them.