I most agree with the "neither, easy" option, but, my situation is a bit different.
I fill the void that my partner creates with his/her dominance/submission. If my partner is dominant, I assume the submissive role, and vice versa. I can go either way, and I'm fine with it. However, my preference is submissive.
In my current relationship, we're sort of a blend. It's really quite odd, I think. My partner and I trade spots quite often, not just in the bedroom, and it's not intentional. It just happens, and when it happens, it's not very noticeable to us. We just fall into the roles. I don't know how to describe it, really.