As a professional guitarist with multiple high-value instruments, I have found the Mono M80 cases to be the best of any case I've owned. The padding is extremely sufficient in all areas, the headlock is fantastic, the texture of the case is great (and waterproof!), there is plenty of storage, and the backpack straps are extremely comfortable, flexible, and easy to hook/unhook. Also, the case is the thinnest of any kind.
I own 3 M80's, an acoustic version for my Gibson ES-175, Taylor 814ce, and my classical guitars, a semi-hollow version for my 335, and an electric version for my solid bodies. I would highly recommend these cases for FLYING. I've never once had a problem carrying them on/fitting them in the overheads, and their slim profile and backpack straps make it very easy to avoid issues with airline agents.
The storage compartment expands quite a bit when you pack it, which is very nice. For reference, the compartment will easily fit a 13" Macbook Pro, but the 15" Retina MacBook Pro just barely fits...so tight that I would pretty much say it doesn't fit.
Great item from a great company + Amazon Prime shipping = 5 Stars!