Sports cars often have good reliability stats, but this could be largely because many of them are weekend cars that rarely see rough roads, a lot of stop-and-go, or road salt.
If you fit, the one you really can't go wrong with is a Miata. Inexpensive, reliable, very involving and fun.
The Honda is more powerful if you rev it, but quite noisy with the top up (if this is an issue). Drive one and see what you think. Handling can be a little tricky--stability control was finally added for 2007.
A Boxster--it depends. Your age cut-off keeps you away from an engineering flaw that kills about one-percent of the engines each year. My personal issue with Porsches is that they're only involving if you can push them, and depending on the roads in your area you might not be able to push them much.
The Z3 is over 10 years old. The Z4 that replaced it has styling that's a matter of taste and electric steering that isn't as communicative as the others here. Reliability stats have been good, but while these are more solidly constructed than the Z3 their systems are also more complex.
Mercedes offers the SLK in this class. Could be worth a look.
A Chevrolet Corvette might be an outside possibility, but a much different character.
I'd drive them all and see which you enjoy the most.
In all cases, thorough maintenance records are a plus. And definitely have a mechanic familiar with the cars inspect them.
I'd be most concerned with reliability if this car will be your only car. If it will be a weekend car, it's much less of a concern.