Again, it depends on personal preference and your use case. Soft covers are cheaper and more low-profile, giving the truck a sleeker look. Although most soft covers are made of tear-resistant material, there are some items that might rip through the covering.
Hard covers are known for their durability and security. Due to the materials that they are made out of, they are often more expensive. And, though they still have a sleek look, some might be a little more raised or noticeable on your truck bed.