I chose Ent, but not for the 'green' aspect. My reasons for identifying with the brethren of my favourite character Treebeard are more to do with a sense of isolation from the rest of Middle-earth's inhabitants. The Ents seem to belong to the world in a different way from the other species, who are all coming and going; but the Ents watch them as they do this. I also thought they would be much more sensible company than the others, who are more prone to childish capering.
Or, to quote my significant other (who may or may not post her own response to this thread):
"Yes, you would be an Ent, all cynical and completely unaware of modern technology. 
"