Paulo Thiago's d'arce on Swick for sure. Most submissions wouldn't be quite as great on pavement ("on the street"), gotta give up position to finish, hard to make your opponent go out, you could get slammed, etc...
But that submission, Swick was out cold in what? Three or four seconds? Paulo Thiago in a dominant, damage-free position the entire time. If I could pick a sub to land every time it's that one.