Simple option: Flat Baseboard Molding

Flat baseboard molding is a simple style, it is completely flat at the front side. This type comes in different heights, from 3.5” inches to 4.5”inches. Baseboard trim back is grooved for easy in installation. Most of this style thickness in 5/8 inch, but the thickness will vary depending on your application.
This simple baseboard should add a more decorative molding or quarter round molding to give a more elaborate look.
Flat baseboard moulding is actually more versatile compare to other moldings. You can use it in almost any style of home, with crown molding, window trim or door casings. You can put another trim on top of it, make it work well with architectural styles.