I've tried cheap, moderate, and pricey. Depends where I'm going and what I'm doing. This is a good question because I have some really specific and unmet luggage needs.

For the past several years my travel has been Latin 3rd world countries, out in the rural areas. Sometimes I'll have to go via panga (small boat); horseback, 2-wheeled carts, and/or chicken bus. The biggest problem that I have found is ot rough handling but the elements: the torrential downpours and mud really can create a problem. Also, I carry medical/educational supplies in an extra (beat-up) suitcase that I always leave behind. That particular suitcase is triple wrapped in duct-tape and the interior contents are always shrouded in plastic.

But the suitcases/duffels I utilize have all failed in some way. The only constant in my life is a Swiss Army backpack (super big, strong zippers) and that I have no complaints about. If anyone has suggestions, I'm listening!