Im pretty sure the M3 has more torque then an NSX - easy for you to check.
The NSX is not known for its torque tho and if you want twisting power, it is not your car.
97+s are a bit faster then then 91-94, and a fair bit faster then a 95/96.
But the difference comes from the engine being a bit stronger, the car being a bit heavier and the gearing being better. You are not going to feel that the cars are dramatically different tho.
You should choose the better deal on the car that you like taking into consideration color, condition, blah blah blah.
Dont forget that OBDI cars are much easier to mod the engine. Youre certainly getting a newer car with the 01 and maintenance should be a bit lighter. Dont forget about snap ring and the windows and if you want a targa roof, then youre forced to get a 95+. If you do want targa, the 97+ is really the best choice. If you dont mind a coupe, then, assuming you can find a great car, maybe the earlier cars make more sense.
Cant really go wrong.