Oak Quarry is my favorite course. Really cool layout, and routing through the rock formations is spectacular.
This is the wrong time to play Stadium, they let it grow at the end of summer to get ready for the fall rush. I only have played it once, 15 years ago, shot 74, declared victory and haven't gone back. Nearly went back there on Monday, but someone told me about the condition so I went to Silverrock instead - great track.
Trump National LA will give you the highest scores, as any wayward shot is lost in the junk. When you do get on a green, you have to navigate elephant humps. It is a borderline stupid course, just forget about the score and enjoy the amazing location and great facility.
But for a great, fair, hard course I'll go with Mission Viejo Country Club. Great course, beautiful conditions, fair but just plain difficult.