Wrath and moonfire are incredibly close right now. Close enough that it just doesn't matter. This will change for 4.0.3, but for the time being, just pick. Doesn't matter.
Wrath and Moonfire? Don't you mean wrath and starsurge?
As much as I appreciate theorycrafting, at some point you have to get out in the real world and kill internet dragons to see how things really work.
Let's look at this parse, for Lord Marrowgar, which is pretty much a tank and spank fight:
If you were to assume that insect swarm was up for 100% of my wrath casts (which in theory it should be), you're looking at another 40k damage for Wrath. My wrath was not glyphed.
However, if you look at the Moonfire + Sunfire damage (even with Sunfire bugged and ticking at a 3 second timer), 73k damage came from the glyph of moonfire.
Fights that are not tank and spank and require movement are even going to inflate the glyph of moonfire even more. On many fights, IS+MF+SunF do more damage then my nukes.
On a fight like this: http://www.worldoflogs.com/reports/36mr7916dy32eeic/details/12/?s=2419&e=2546, which is the ULTIMATE tank and spank fight. (I didn't switch to blood beasts and just nuked Saurfang for about 22.3k DPS).. the glyph of Wrath would have given me about 73k bonus damage, and the glyph of moonfire gave me 61k. So, for an ultimate tank and spank fight where you just stand there and do nothing but nuke the piss out of something, you may get a little bit more bang for your buck, but that's about one fight in ICC, whereas the other 11 you're going to get more worth out of glyph of moonfire.