Natural wood is considered by many the most attractive siding for storage units. But wood exposed over time to water usually rots. Some woods, however, contain natural resins that make them relatively rot-resistant. Cedar is such a wood and very popular as a siding choice for storage units. But even cedar siding is not maintenance-free. Coat cedar with a UV-inhibiting sealer/preservative every other year to protect it from ultraviolet solar radiation. Apply a clear stain, as well, to help preserve its natural beauty.
Remember that these structures are not merely for storing things away. In addition to their usefulness, the appearance of fabulous shed with side storage affects the overall appearance of the property on which they are installed. As such, the unit you choose should be of a design that complements your home. Select one with a rustic design (for instance, board and batten) for a country-style house. If your house's style is more formal, select an fabulous shed with side storage with formal features to match (for instance, if your house has an arched window, carry the theme over to your outbuilding).