I've actually owned both at different times, and in '73 chose a Z28 over the Cuda; the quality seemed a bit better on the Camaro.
Plus our family got a helluva deal on GM cars, as Dad's consulting company worked on their healthcare plans.
It was a rare gap for me in terms of Mopar ownership. Possibly the Z28 was faster than the Cuda that year, don't recall.
If I had it to do over, it'd still be a tough choice.
Ironically perhaps, they bring similar money now for a nice one.