I also included "Myriad" because Google was constantly automatically "correcting" me to that, so I think it's relevant to include that data too.
I think the above chart shows that Miriad and DragonFly are not very good choices in terms of originality / confusion risk / easy to find with a Google search.
Dragora, Myridon and Pyragon are very good choices. Pandragon, Pyrrha and Pyra are intermediate ("Pyra" is actually worse than "Miriad" if you consider only the actual query, but at least it does not get auto-corrected to something else).
If you take away Myriad and DragonFly from the above chart, you get this: