The best is a firm plastic coiled tree wrap that is able to protect the tree trunk from getting damaged by rutting bucks. This is because deer are considerably taller as compared to rabbits and they can also stand on their hind legs. Find more details here http://www.ehow.com/about_6327621_tree-wrap-rabbits-deer.html.
I have tried a lot of spiral tree wraps, but a product called Tree Armor worked the best for me. Its not only a spiral shape, its tapered, which keeps the plastic from spreading and allowing gaps for the deer to chew on,. Its also brown which makes it pretty invisible. I love it