Well, its obviously a matter of personal opinion, but having driven all the cars I mentioned above I would choose to own the RX-8 last. All of the others were faster, got better gas mileage, handled as well or close to as well, and could be had for around the same price.
I did like the interior and rear doors of the RX-8 the best, but that was about it. I am a huge Mazda fan and have driven many past RX-7's, miatas, MX-6's, MX-3's, etc... I'm just not at all impressed with the current car.