Even if I like Stan, I would go with Tsonga here - GS Final in an early attempt, already had a Masters, I think has the best tournament record against the Big 4 among those said.
But the game is constantly changing. When Tsonga made the semis Djoko and Nadal werent this frighteningly good. Wawrinka is the only player this year to have pushed djokovic to 5 sets and twice at that and thats with a one handed single backhand. In modern day tennis this is a shot that will guarantee you forever stay outwith the top 10 as the forehands are too massive now and achieving control requires supreme technique, hence why I say wawa is a more technically able player notwithstanding the results