[Polygon]

Well, it really depends on what you want to car to be able to do. I'll give you some advice for each on of these cars.

4th gen Camaro/Firebird with an LT1: They are really good, cheap power. They are respectably reliable. However, they're only really good in a straight line. If you like to take on the twisties I suggest you steer clear of any Camaro/Firebird.

3000GT/Stealth Twin Turbo: This might sound biaed simply because I own one but it's a great platform for the money. Just do your homework before you buy as these are reliable cars, if they've been taken care of. They are a bit on the heavy side at about 3,750 pound for the TT models. However, you have to consider it a DOHC V6, two turbos, two intercoolers, all wheel steering, all wheel drive, active exhaust, electronic suspension, and they have a pretty decent interior. It's very easy to lighten these things up. It wouldn't take much to get one down to about 3,300 pounds while keeping the AWD and AWS. The only real downside to these cars IMO is the fact that they aren't the easiest to work on under the hood because it's kind of cramped. As for making them faster, it's cake. Plus a healthy one will go from 0-60 in 4.8, the 1/4 mile in 13.8, and have a top speed of 160MPH. Get a little over 500HP to the wheels and the car is capable of a hair over 200MPH.

300ZX: Think of this like the 3000GT/Stealth but the only real difference is they are RWD.

Fox Body Mustang: Same deal with as with the Camaro/Firebird.

Miata: Like you said, this will never be able to be as fast as any of the others. However, the thing is like a go kart and can be a real blast to drive in the corners. Excellent choice for auto-x where power isn't as big of a deal.

If you want to drag race go with the Mustang or Camaro. If you want goo all rounder go with the 3000GT or 300ZX. If you want to auto-x and save on gas get the Miata.

Personally I would go with the 3000GT or 300ZX simply because I like the twisties, but I want to have decent straight line as well. Plus they're great to drive on a daily basis. Also, food for thought, the Dodge Stealth R/T TT is the same car as the 3000GT VR-4 but will cost a lot less. However, it will not have the active aero, but the Stealth spoiler produces more downforce and the AA is known to break.