Between those two, I'd go with the JBL's. Klipsch speakers are too "bright", for my tastes. Paired with a Yamaha receiver, would be extreme brightness, because Yammy's tend to be on the bright side. Need to pair a bright speaker with a warm sounding receiver, and vice versa. If you have Best Buy or Circuit City nearby, go there and listen to the different stuff they have. Listen to anything that is available...........
Good luck!