Fun-to-drive is a convertible, right? If so, go get yourself any 92-02 Viper RT/10 and enjoy it. Buy on price, condition, and miles and not so much on year as there is not a huge difference across the years. The 97+ RT-10 does have a few nice things like glass windows, more availability of hard tops, standard OBDII 450HP GTS engine. The 95 and down have the advantage of being true collector cars, cheap to buy, and side pipes!
I have gone from a supercharged C5 Corvette (fast, always broken, just another Corvette) to an E55 AMG with everything done to it (fast, relatively reliable, no presence) to a 95 Viper (slow and hard to drive, reliable as gravity, more presence than Andre the Giant)
If you wanna be snapping necks, get a Viper.
An NSX is cool and they are fun to see, the other little coupes (Lotus, Noble, 4C, etc)are neat to see as a car guy but are invisible to average derps and most lack a removeable roof which for me is imperative for fun
R8s are pretty cool and still look modern and expensive.
I would suggest staying away from Mercedes and sleepers if you want attention. Monster Miatas are a dime a dozen to plebes because they look like regular Miatas, Mercedes AMG offerings only get noticed by enthusiasts since that was sort of their whole schtick.
Also, at least in the rust belt, the Viper gets a lot more complements from your average pickup driving Joe the Plumber than a Ferarri, Audi, or Lambo ever would since it was a halo car of a domestic brand vs a car for rich white shiny happy people.
...My ride to work today...