This is a tough choice, in fact I am still debating whether or not to even vote. When I saw the initial list of ten nominees I thought, as I believe did Orlok, that none of the nominees were what I thought of when thinking of a romance novel. I was expecting a book with a picture of a bare-chested hunk holding a beautiful woman on the cover.
Well so anyway looking more into Outlander it seems like a potentially entertaining science fiction/fantasy time travel novel. If, as write ups on it suggest, the author went to great care to accurately describe the reality of life in mid-18th Century Scotland I might enjoy this as a real change of pace. It sure does not strike me as a romance novel though. It is actually available as an ebook from my local library, but with a long waiting list.
The other possibility is Tender Is the Night. I have not read it, but also I would call it more another in the classics genre rather than a romance.
I will have to think about how to, or even if to, vote.