The difference between the toughness of the blades and the springs of the farmer and the huntsman aren't really that much. Sure, the farmer has a slight advantage in toughness but whatever the farmer's blades and springs can take, those of the huntsman can take as well. So in my humble opinion, the toughness difference there is too minimal to be of serious consequence.
The real "toughness and durability" difference comes from the scales. The typical cellidor scales of the huntsman is way way waaaaaay weaker and far far faaaar more fragile than the macho aluminum oxide scales of the farmer. This is where the durability difference lies. And for some people, the toughness of the scales = the toughness of the knife. So to some, weak scales = weak knife.
This is why if you want to choose the huntsman, in order for it to be more competitive in terms of scale durability, choose the ecoline version. These are the ones with the "cheaper" nylon scales. Sure they are cheaper, and to some, they look "cheaper" in the quality sense, but in reality, their durability is outstanding.
The next consideration is the tools. Of all the tools, the real loss when it comes to choosing the farmer over the huntsman is the scissors. And for a lot of people, it is a real loss. You'll see a lot of articles and comments all over the internet praising the scissors as the most used of all the swiss knife tools. And there is good reasons for that.
The last consideration is the thickness. The farmer is far thinner than the huntsman and that could be a good advantage.
So it really depends.
If you care about the thickness, i.e., you don't want the knife to bulge in your pockets, hands down, choose the Farmer.
If you need the scissors and maybe you want the corkscrew and the eyeglass screwdriver, choose the Huntsman.
If you care about durability, it doesn't matter which one you choose (depending on the above choices), as long as if you choose the Huntsman, get the one with the nylon (ecoline) scales.
Cheers.