I give it to Liu Juan for a very very slight majority.
As Bad Ass as Mad Dog was, in that final fight what people have to realize/remember is that the criminal brother had lost a lot of blood and was very weak from having been stabbed through the hand, and being tortured for anywhere between 20 minutes to an hour or more depending on how time went by in the movie.
The Cop brother on the other hand was exhausted from nearly non stop fighting. His muscles were probably screaming by this point and the simple fact that he was walking without painful cramps is a miracle.
But Mad Dog was a physical beast, and was probably smoking some very very potent crack or opium to be as durable as he was, so his stats were probably amped.