I think the most critical aspects of such an analysis are setting and characterization. Glint was created for a certain purpose, and acts out her role in a certain area among certain conditions. The same is true for Kuunavang, but her skills and purpose are different, and as such comparing the two seems difficult, at best. Because Glint's primary role was that of guide and aid to the Chosen of Tyria, she places the survival of the heroes above her own anger at being attacked. This Glint is polar to the Kuunavang corrupted by Shiro Tagachi, a very manic and aggressive dragon who excels and revels in combat. Once released, however, Kuunavang is dedicated to defeating Shiro, and aids the heroes in doing so. Now, why is all this important?
First of all, based on the above statements, Glint and Kuunavang would most likely never fight under normal circumstances. Kuunavang is too removed to come into contact with Glint, and even were this to happen, Glint would most likely refrain from doing battle in order to maintain the balance brought to Tyria by the Chosen. The exception to this would be if Kuunavang were herself a threat to the balance, but since she is fairly quickly released from Shiro's corruption, this is unlikely.
Based on in-game skillsets and experience, I would rule in favor of Kuunavang as a likely victor. Her offensive capabilities seem to surpass those of Glint. Yet we don't know much about Glint's defensive capabilities, so the battle could very well take a 180-degree turn. There is much left to be discovered, and I think it's foolish to conduct this debate solely from the angle of gameplay. Such reports rely heavily on point of view, which is in turn heavily dependent on the actions of other team members. A discussion of this type of lore requires inference and outside contemplation in addition to screenshots and statistics. My interpretation of the lore causes me to rule in favor of Glint from that perspective.
Timeless
P.S. This is my first post in the Lore forum, but I've been lurking for a while and I'll be posting quite often from now on.