just like 8uviper, I currently own both NSX and Supra tt, i would like to provide some feedback if i may..
First of all, i would have to say i love them both. And i can not really tell you which one i like better. It is like your sons or daughters, they are their personality & their own traits..
Remember, this is NSX forum, most feedbacks i read here are are very biased. Not very fair at all.. eg. style (apparence of a car) is in the eyes of beholder.. and Supra is NOT a merely drag car, come on. People think Supra is only a drag car because of its hp/tq, and it tends to leave heavy impression for its acceleration ability. Most fellow supra owners that i know do a lot more than just drag race. I use it for other stuffs.. like geocery shopping, carring more than 2 people, etc. Can you do that with your NSX? 
anyways.. My opinion:
Supra advantage:
- 400 rwhp / 400 tq at less than $ 800 mod. There is nothing like it when both turbos kick in.
- reliable, inexpensive to maintain.
- outstanding track car, very forgiven
Supra disadvantage:
- relatively heavy- 3,550 lbs
- king of Riceboy (thanks to all boy racer) riceboy try you race you ALL THE TIME.. day/nite, gets really old..
- so many young kids have it now days, dont feel as special driving it.
NSX advantage:
- exotic dream car for many.
- style is for everyone, even for ppl dont know much about cars
- MR, great track car once you learn how to master MR
NSX disadvantage:
- So pricey
- expensive to mod, expensive to fix
- for a lite car, it eats tire twice as fast as supra... OUCH
Again, to me, they are both wonderful cars. And i am lucky to have them both.
-jjc.
93 NSX 6 spds (stock + 6spds)
93 Supra 6 spds (heavily moded- double rwhp & tq of my NSX)
