Since I am still trying to obtain both of those mounts, and have seen them many times...
Honestly, I vote the Wyvern mount. It has more variety to it than the Bone Dragon. There are different colors, and it's just not as boring as the Dragon.
Even though they are both cool, and hard to obtain, I like the Wyvern Mount best :)
which would you prefer life or death? i say that because, they are the same graphics, but one with skin (even the idle movement is same, minus fireworks) and one without, so to me, thats the big question. i would rather wyvern though
i think the bone dragon is better. Because with the wyverns you have a what? 5x better chance of getting one? While there is only one bone dragon. My bone dragon is faithful and uh, dead. So i'll stick with him.