I never really knew how to answer the question, but from hanging out with people who played video games and watched Avatar it naturally came up a lot. The consensus among multiple groups seems to be something between water and ice, so I'm just going to call it "Water". If not for it having come up with the same answer more than once (one person posed electricity and another earth, but they ended up dropping the notion from parts not fitting), I'd not have really thought about it as much since it was picked from the whole "each person can only be one element" notion.
Water came up for me related to temperament, the ability to adapt, and one referenced how it's ability to turn into ice is like my snapping into rigid views, while I thought to myself that the vapor state is like when I'm dissociating really badly. I also keep dating "fire types", chilling rage and fear and turning it into something useful while their passions meanwhile keep me in check, but they seem to see me closer to "ice" than "water".