Chrissy,
Like Jess, and for the same reason, I think it would be Spanish.
I have not had much success learning other languages. I took one year of Latin in high school. I tried to learn Korean, which is a very structured, and compared to other Asian languages, modern. And, I have tried more than once to teach myself Spanish. All of my attempts of ended in frustration. I too will stick with English at this point in my life.
Gwen