I guess I will have to put in my $.02, I have owned a '91 and now I have a '97. These 2 cars may look alike but they are very different. Most of the time ppl will tell you to buy the newest car, but it depends what your buying it for.
PRICE: '98
You didn't say the sale price of the cars but only that they are very similar priced. That being said I have to assume that the price is probably high $30K or Low $40K, either way I see it as cheap '98 or expensive '91. I would just buy both and in a couple of years when the economy gets better sell the one you don't want and you might just make money.:biggrin:
DEPRECIATION: '91
If you are planning to keep it as a garage queen, and are thinking about selling it at Barrett's in the next 10-20 years, I would think that you could fetch more money for the '91 with less milage, but also IMO you won't loose much either way b/c I believe nsx will appreciate, especially since Honda is not comming out with a NSX replacement but more of a GT car that will compete with Porshe panamera, GTR, Lexus LFA etc.
DRIVEABILITY: '98
I really like the NA2 compared to my previous NA1. For example things like PS, I really didn't care for it at first but now with it I don't know how I could live without it, turning the wheel at dead stop is so so easy, plus when you get up to speed it becomes like the na1 steering, very responsive.
3.2L engine is nice, but 6-speed is nicer. I feel like I'm in the power band all the time. No more "lag" in 2nd gear.
T vs Coupe: '91
I personally don't care for T top. Less rigid, more likely to leak. now if I could of found a NA2 Coupe that would be dream!:smile:
Although if you like open top it may be for you.
Modification: '91
I think OB1 is easier to work on than OB2, so if you plan to SC or Turbo the car, I would think why spend the extra $$ for a NA2. That said I hope to SC my car.:biggrin:
On the flip side if you ever want to convert the car to '02 look (I've noticed more and more ppl doing), the '98 would already have the 6-speed and 3.2L. So all you would need is front and rear cosmetic body parts.