I personally prefer Nylon as I've found over the years that compared to HDPE, it's better for load-bearing and structural parts as well as for wear resistance. But that's not to say that HDPE can't be used, your two cases of Tormenta 2 and Inertial XL being examples of HDPE serving well.

Ultimately choosing between the two can also come down to personal factors. HDPE is cheaper, lighter and easier to work with than Nylon so it can often boil down to what suits the budget best.