I would never use metal corner bead now that vinyl corner bead is available.
Go to any place listed under Plaster & Drywall Supplies in your Yellow Pages phone book and you should be able to find Trim-Tex vinyl corner bead. (Phone ahead just to make sure they carry it or a competitor's equivalent.)
The advantage of vinyl corner bead is that it doesn't dent the way metal corner bead does, and therefore if it gets hit hard enough to knock loose from the wall, it snaps back into it's original shape, and you can sneak some mud back under it and stick it back on again.
You can't do that with metal corner bead. Once it's bent, it's permanently out of shape and has to be replaced. And it's also a fight cutting out the damaged section of metal corner bead because it's so thin that it's hard to cut the damaged stuff out without bending the straight stuff and adding to the damage. (You pretty well have to cut it with a small thin abrasive cut-off wheel made for pneumatic cutting tools for plastic and metal. You can often mount one of those in an electric drill if you can find a mandrel that will fit. Or, my own experience trying to cut metal cornerbead without creating more of a problem was one that tested my patience.
Also, you don't NAIL vinyl corner bead on, you can put it on various ways, but I like to glue it on using drywall joint compound mixed with white wood glue.
Drywall joint compound is soft and weak, but when you mix white wood glue into it, it dries quite strong and impact resistant and is actually slightly "elastic" so that it will bend and stretch an imperceptable amount. (You get the same result with "polymer modified" thin set mortars and grouts; they add powdered glue to the mortar to make it stick better and have more strength and elasticity than the masonary material would otherwise have. "Polymer modified" simply means "we added a polymer to it" and that polymer is normally a glue in powdered form that becomes activated when mixed with water.)
You just spread that sticky mud into the corner of the corner bead and onto the exterior of the corner you're working on and simply press the corner bead onto the corner. The excess mud will come oozing out of the holes in the corner bead flanges, and you just collect it with a putty knife.
When I do this work, I first remove the excess mud that oozes out with a putty knife, and then wipe the corner down with a damp sponge. Then I put several strips of 2 inch wide painter's masking tape around the corner to hold the bead tight to the corner as the mud sets. The next day I pull off all the tape and the corners are ready for their first coat of mud.
You could use fiberglass mesh if you want, but I never do, and I have never had any hairline cracks along the edge of the vinyl corner bead. I think that's because the corner bead is glued to the drywall, and so there's never any relative movement between the two that would cause a crack to form.
Try both, and decide for yourself which one is better. I've installed more than my fair share of corner bead too, and I won't touch metal corner bead anymore (except to push it out of the way to get to the vinyl stuff). But, as with EVERY new product, there is always resistance to accepting it because everyone always thinks that the way they've been doing it for years is the "right way" to do it, and anything else must therefore be a short cut and inconsistant with quality work. That's why you need to make up your own mind, not let anyone else make it up for you.
Trim-Tex now makes a line of metal corner bead made specifically to be glued on with drywall mud just like I've been doing for years. They're called "Mud Set Beads". Someone at Trim-Tex musta read one of my posts and stole my idea. I'll sue.