Dominant, definitely seeing a partner squirm and whimper and get needy. Makes me want to tease and coax more reactions like that out of them.
As for submissive, it's usually needing to be teased in a certain way, not immediately taking control away but doing it slowly and gently, teasing about my wires or similar.. I don't get submissive very often and not many people really have done it in a way I enjoy.