Cove molding is the simplest and most common.
Crown and bed molding are decorative profiles that can provide a traditional appearance. Like ceiling moldings, they can be combined for a traditional look. Base moldings are often used in conjunction with a base cap, a small decorative profile that is applied on top of the base to finish the look. Again, wider moldings tend to make a room look smaller, so avoid wide base moldings unless your rooms are spacious. Casing profiles often match base moldings, except casings are rounded on both front edges, while the lower edge of a base molding is square to keep dust out of the joint between the molding and the floor.