I only do carry-on, so I need a good bag that will compress contents and is sturdy enough to check when required. For that, I have had great success with my 19 inch hard shell IT bags. We have 4 people in the family, and fly round trip 3x a month. Been all over the world. These bags take a beating and always fit in bins or under seats. Plus they are always the easiest bags to spot when checked.