cxd5 or c5?

I usually do cxd5.  Sometimes I find that pushing the pawn to c5 just leaves him hanging, but it depends on how your opponent plays.

If I remember correctly, c5 is not good if the rook in the corner is not defended, since White will not be able to keep that pawn wedge intact.

In my limited experience, even if White does establish that pawn wedge, Black usually finds enough space to play on the kingside instead. With the tension in the center released and c5 being a non-developing move, that should be decent enough.

I'm a bit at a loss as to how c5 does anything to restrict the g7-bishop, actually. It controls the vital e5 square just fine and is hardly obstructed by any of Black's pawns.

I don't like c5 here. Black could eventually play e5 and exd4, and white might as well paint a huge target on the head of the d4 pawn. This is assuming Silfir suggestion wouldn't work as well for some reason.