It all depends on your taste. Mazda has already lied about the HP output on their suspect rotary engine. The crossfire probably has a better interior. The only thing I liked better on the RX-8 was the back seat. I'd say there was almost as much space back there as in a regular sedan. It was very roomy. But other than that, I'd go with the crossfire on everything. Now the 350Z is another story. It and the Crossfire are very close in my opinion. I would definitely put them in this order:

Crossfire
350Z
Honda S2000
Audi TT (Supercharged version)
Mazda RX-8

But this is just my opinion.