The gap between each car, especially between e36 z3, e85/6 z4, e89 and new g series is generational. Having driven them all they all have their pros and cons.
You can’t relax and drive a z3, so if you enjoy that level of involvement it’s for you.
The 85/86 is usable as a daily, plus with all the facets the guys above note.
The 89 is a step along the journey again with levels of comfort, dare I say detachment from experience and refinement.
I drove a g series m40i and found it to be a very similar experience to all g series cars, but not for me
So it’s what suits you and floats your boat… with a broad church to suit all tastes what’s not to like?