If one urban legend creature could actually exist (assuming in fact that they do not) which one would you want it to be and why?
My flippant answer would have been "all of them," but that's not really true.
Over the course of my life I've certainly done a lot of reading, research, and writing about legendary creatures, but aside from my fascination with them, I don't believe that many of them actually exist.
My top pick would be Bigfoot, but I actually think that compiled evidence supports its existence, and that it just hasn't been proven real. Anything you get from a newscast is not going to be fair, balanced, or even informed, and will generally bunch in any possibly valid sightings, or evidence in with unfortunate, and obvious, hoaxes such as the refrigerated bigfoot corpse from a few years back, or bad television shows like Finding Bigfoot, which my son calls "Faking Bigfoot." If you ask any scientists actually involved with evaluating gathered evidence, you will reach a very different conclusion.
Since, I'm certain that Bigfoot exists, the sasquatch is not my choice for legendary creature I wish were real. For my answer I give you:
THE SEA SERPENT (though I'll gladly take lake monsters) such as our local beast, the Gloucester sea monster seen above. I've read enough accounts of sea monster sightings to find them a compelling mystery. On one hand, I logically think no way. On the other hand, some specific animals had such regular and frequent sightings by a vast number of people, including experienced maritime folks, that they had to be something, and misidentified existing animals don't really fit the descriptions. I don't think they were dinosaur like reptiles. Maybe they were once real, and are now extinct.
Creatures, such as the Loch Ness monster I find less credible, but again, maybe they were around, and once people surrounded their habitat they died off. Again, I don't think they were surviving plesiosaurs, but they could have been unknown animals.
Overall, I find them to be more legendary than likely, but I'd sure like to see one.