Of this list, I think Ballin has had the biggest influence over the games they've played.
Folau has scored a couple of tries (one or two gimmes, some bombs, and some good efforts) but he's a winger....his impact on a game is minimal. Ballin has been pretty much outstanding in his two games, great dummy half service, lots of tackles, kicking game out of dummy half....
I think it is to be expected that he is the pick of the bunch though. He is older, more mature, in an important position and in a winning team.
Wallace has gone damn well as well however.