I've found the type of bag that has straps around it instead of handles on top to work better for me. First of all, the lid will never be under stress. That makes it last a lot longer. Also, the lid surface is not blocked by a handle in the middle of it, making it useful as a workarea (put all my calculations on the lid and use it as a desk). Also for planes not equipped with tables, it makes for a nice dinnertable!
I guess spacewise, the more space you have, the more
you'll bring.
/LnS