I prefer NA's than boosted cars, the GT2 is way too expensive and way too scary to learn of its dynamic capabilities. The GT3 however is easier to learn at the fraction of the price, plus its way better looking, and not much of those electronic nannies to help you to drive hard in GT2.
Does it really matter?
You can equate just about any Porsche (924's aside) with sex.
Even bad sex is pretty good.
Just pass any unused/unloved running Porsches in my direction with titles, registrations, and keys. (That includes 914's)
I'll take care of the insurance.
We're talking about an ideal world here. You know, the one where you have bags of cash, can fly, see through dresses and make women swoon with a single glance?
In that world which is marginally more appealing to ya?
The GT2 has nearly 500 HP and the GT3 "only" 360. Only 100 (or 150 I don't know) GT2s have been delivered to the States. But the GT3 is more lighter and so better for tracks. The GT2 is the faster car but experts say that the GT3 is better for long-distance-circuit-driving.
It all depends on the track. If I were going to a long, straight, high speed track, I'd take the GT2. But a curvier track, or especially a mountain downhill (closed course, of course, I learned my lesson the hard way) I'd take the GT3.