On a real track with turns, the Z06 would annihilate the GT500. If you are referring to drag racing, from a dig, the Z06 would also be superior due to much better traction. From a roll I'd say the GT500 may be the winner with its limitless power.
Between the 2 I'd pick a GT500. Cheaper, easier to mod, seats 4 and the C7 corvette is right around the corner.