Most of the Pros who travel use soft cases. Soft cases can be squeezed into spaces a hard case won't go. The best bikes are shipped to dealers in cardboard boxes. I've used all the Bike Pro soft cases and they're on the bulky side. The best is the Sci-Con bag that is pretty trick. All you have to do is turn the handlebars and remove the wheels and the bike is in. It even has a second fork mount for mountain bikes. It has a special guard to protect the derailleur. It received favorable reviews from Leonard Zinn and is used by the Postal Service. Best of all they can be partially folded up.
Hard cases are a pain but I suppose they offer the most protection. Most of us have not had bikes damaged in soft cases so we're not willing to put up with the inconvenience of a hard case.
Del Mar CA