Drive them both, back to back if possible.
I have a 2003 M3. I used to have a 1993 NSX.
The M3 is a great daily driver and a lot of fun. It offers a lot more in usability and practicality over the NSX.
That said, it is only a matter of time until I have another NSX, and if the M3 has to go, the M3 has to go. It would be nice to have both, but if I could only have one, it would be the NSX.