Am I the only one who likes 6 because of those big green eyes and the way she's licking her lips? It's like, "Hello there tasty~"
Although I guess I'd have to vote for 1 or 5. I love the lengthy blonde hair on 1, and the design of her horns is the best, plus her expression is adorable. Also I'm a sucker for that particular skin tone, though the speckles on her skin don't really do it for me. I really love the contrast for 5 with the dark skin, dark teal eyes, and then vibrant pink hair. Plus the fact that she has a ribbon on one of her horns is adorable. Yet at the same time the moss (I think it's moss?) growing on the top of her hair makes it slightly less appealing? Her horns seem to be the least tree-like though, which I actually really love about your other designs.
So I guess 1 gets my vote because those horns are absolutely fantastic, and I'd LOVE to see a full body portrait of her.
Numbers 3 and 6 look the most fitting to me. In my eyes, their antlers seem the most realistic. #3 (dark blue skin) looks most like a hybrid of deer antlers and tree branches. #6 (lime-green skin, blonde hair) looks most like a combo of a deer and your concept of a dryad, along with a tree's thick strong trunk combined with the power of a buck's antlers.