I've heard (and seen) that "Garden" has been a finalist several times, and personally I like it since those one-word themes appeal to me. Noting how "Garden" doesn't specifically mean a bunch of flowers surrounded by a little fence that you don't want to mow over, I think "Garden" could be a big surprise theme. (Like how most everyone was excited for Stuck In A Loop at first but regretted it in the end, and vice versa for last Ludum Dare's surprisingly great theme)