Hi,
I don't use Canon - so I don't have that setting to play with!
I usually have the camera set in the auto mode for everyday shooting - only change things when subjects are backlit, macro, or looking for a specifice effect i.e. blurred water effect in a waterfall photo etc.
I am a great believer in using what comes out of the camera - other than a bit of sharpening and a crop here and there.
Good camera, good glass and a good technique should give good results....Simple eh!