Which would be better for a large wooden storage unit: hardwood or softwood?
In general hardwoods are used for upscale furniture and not for your typical storage unit. A soft wood will work just fine and be more economical. In fact, a plywood would be a possibility depending on exactly what the design looks like. It is cheaper, more stable and comes in several materials besides pine such as ash, oak, birch and even cherry or mahogany. If the design is done properly using a combination of solid wood and plywood can result in a very attractive piece of furniture or even a very nice storage unit. If there was more information it might be possible to provide better advice.