I prefer Oakley. Since I am a sales person at a retail shop and we get a lot of dragons in for warranty. The coating on the lenses is not very strong. So they are much more noticeable when they just get a little scratch. Moreover, the construction of Oakley lenses are much higher. That is to say, Oakley goggles are much sturdier and more resistant to noticeable damage. Both goggles need to be treated properly to last a while, but generally speaking Oakleys hold up season after season much better.
Frankly speaking, you can't really know if you like Oakley goggles or Dragon goggles until you actually use them. Once I bought a pair of Oakley goggles and they have been great. Any fogging clears as soon as I start moving and they are very comfortable. They have double lenses, and are optically correct. I have not tried Dragon goggles at all, so I do not have any idea about it.
To my way of thinking, Oakley goggles is better, I have a pair of Oakley.a frame that I bought about three years ago.the foam on top has almost completely disintegrated and let snow in on my last stormy day but they still don't fog up,that's amazing.