Made a mistake when I chose an E46 M3 over a Z06 approx. 16 months ago.
6 months after that decision, I corrected it by trading it in for a new Z06.
Having owned both, there's no comparison when it comes to performance, and surprisingly, respect from other car enthusiasts.
Every 2nd ricer wanted to race my M3. Was getting tired of it.
Now with the Z, they all look the other way, or don't pull up beside me, or take a turn. On the track, a modified Mustang I spanked was convinced I used NOS on our run, and had to prove it to him by flipping open my hood. Boy did he walk away quickly with his tail between his legs....
I still have a thing for the E46 M3, and if I could afford it, I would own both. But alas, my financial situation makes that difficult.
So if it's the M3 or Z06, there's absolutely no hesitation choosing the Z. She never fails to bring a smile to my face every time I see her in the garage.