Having access to both i might be able to offer a lightly unbiased opinion.
1991 NSX, 17/18 Advan SAR3's with JIC FLA2 Coilovers, Intake, stock exhast.
1997 GTR VSpec HKS Intake, Kakimoto Exhaust, GAB Coilovers, 18x9.5 Wheels/MonoLug Conversion
NSX, definitely better handling (because of weight difference) more responsive, easy to control, underpowered. gets the looks from the porsche, vette, ferrari owners, and the girls. This is the car i would take to a autocross event. this is definitely a keeper. 6sp converision & 3300 ~ 3400cc conversion in progress. this car is daily driven.
GTR, definitely more power, and more power potential. too heavy. get the looks from every kid with a riced out civic. they chase me home, i have to do over double the speed limit, and loop my neighborhood twice to lose them, if i dont they call their friends on their cell phones, and they multiply.
This is the car i would take to a drag race. This car is for sale $65,000. Also has Greddy front lip & side skirts, bomex rear lip and lip spoiler, Nismo oil cooler with optional ducting kit for cooler. Pioneer DVD system, Greddy guages, and Bride Seats. Its white, and has Signal Auto broken-up stripe package, carbon door garnishes, polished valve cover and turbo bits, Uhhhhh, i'm probably forgetting more. Its the fully loaded Vspec model with the factory HID headlamps, really clean.... have some slotted rotors, and performace pads on the way too. forgot how many Km it has, but it isnt a whole lot. email me and i'll get you more details.
-Ray