First of all, I think its pretty difficult to make torque without making about a similar amount of horsepower. They're simply mathematical derivatives or one another, not separate entities. This has been debated to death, and both are important on the street.
Simply: torque is work, ie, how much work can you do? How much brute power does the motor make?
Horsepower: How fast can you do the work?
So how much torque do you need? Enough. How much HP do you need? As much as possible!