Depends on what you're going for reliability, speed or handling.

all the above mentioned cars have their own plusses and minuses.

I personally would never buy the Miata without it being the Mazdaspeed version for the HP and handling (also check out the wheel gap on the current Miatas ).

S2000 is a great handling damn quick car with reliability.

Solstice looks ok (I like the sky better), is very fast, handles ok but hasn't been great reliability-wise.

 

Well, you want some gap in there. If it's too tight (as many aftermarket tuners find out) the tire will rub inside the fender well on bumps and corners.

The base Miata, while admittedly not as fast as the Mazdaspeed version, is no slouch when it comes to handling either. It's a pretty good slalom-buster in its own right.

Yes, it handles, and is reliable, but the normally-aspirated VTEC four is enormously peaky. There is little torque until you carry the RPM to absurd levels....and then the HP peak all comes on, more or less, with a rush.

Most people do think the Sky looks better (I also agree). The Solstice has a odd split-front grille that, IMO, looks a buck-tooth beaver.