No one. Sony's face was Crash, and now he's not. They never needed a face anyway. The PlayStation legacy is based on appealing to many gameplay-types.
However, Kratos has been made into the de facto face over the simple fact that he's the face of Sony's action titles (which lend themself well to this game) and PSASBR is being co-developed by Sony Santa Monica.
I like to make PSASBR move-sets. Here's a few:
Never say I don't contribute: I'm The Idea Man.
Sweet Tooth, since he has been on all playstation platforms (LONGEST RUNNING PLAYSTATION FRANCHISE), everyone else has been on only a some...although, sackboy appeals to all gamers since he can be any genre and can even dress up as the other characters...playstation