I use both. For my acoustic, I have the hard shell it came in and use it when traveling overnight. If I'm going to a friend or local, I have an skb gig bag-which is highly structured/semi hard shell. It's lighter weight and is an excellent in between from a hard shell and a typical gig bag.

for my electric-I indulged in buying a reunion blues gig bag. I don't travel overnight with it-only local and only by car.