I do 15-20 round trip flights a year. Not too much, but I am a Tour Guide and I spend 150-180 days a year on motor coaches and in hotels. So, my suitcases get handled a few hundred times each year. I have used three different Sampsonites in my 13 years of doing all this traveling and two of them are still in business.
I would say that they are extremely durable. Their weak spot, in every case, has been the zipper pulls, which seem to be pull off easily. The zippers themselves are strong but the pulls seem to disappear, usually just the small side pockets, which do not necessarily render the suitcase unusable.

For the money, Sampsonite fits my needs pretty well.