I would choose Dragonite, it's a strong good Pokemon and even though they are both Dragon-type they would be stronger then each other I think that Dragonite would be stronger overall.
i pick dragonite cuz i got a dragonair in heartgold from a friend (we traded) and i trained it for a while, it evolved, and i trained it some more now itz level iz in da 80z (i uzed 0 rare candies, juzt training!)and pluz dragonite iz cool