When I was traveling more, I quickly learned the advantage of a backpack style carry on. Beats wheeled luggage by a mile. I have an older Patagonia MLC bag which I wouldn't trade for anything - the new ones have lost their shoulder straps, which is a crime. For checked luggage, hard sided wheeled is probably better, but I don't like to have more than one wheeled piece with me - way to much trouble to negotiate two through an airport.
I am a frequent flyer and carry the MLC bag as well...I use a roller computer bag and just put the MLC on that and go....for my travels the soft sides bag is great because it goes in places that roller bags will not...and in today's airplanes overhead space is valuable.