Grill ridges are generally purely visual and designed to make grilled meat more appealing. Though grill marks don’t add much to the flavor, they create these famous slightly charred lines on steaks, chicken breasts, and fish fillet that look rather pleasing and make for a professionally-looking presentation.
So if you are struggling to decide between a smooth griddle and ridged griddle based on flavor benefits, there simply is no difference and you can go ahead and choose whichever looks more aesthetically appealing to you. Those who plan to use a griddle primarily for breakfast foods might as well go straight for a smooth-surfaced plate.