Actually the case isn't all that important. The main thing to consider is how far is the guitar going to fall and what is it going to land on after the fall. If you let it fall into a large box of goose down you probably wouldn't even need a case.

Actually I tend to agree with Allen C. and the other folks advising the hard shell case. The guitar is probably more likely to be damaged from crushing rather than falling. One other thought, I had a friend who used his martin case to sit on ~ that is definitely NOT a good idea.

Cap't Bob