The NA Miata might have only been a good copy of the Elan, but I think the NB Miata was a step backwards in terms of styling. I never liked it. NC is another step forwards.
My top vote would be for the C5 Audi A6 was the first and perhaps best execution of the classic Audi shape from the 90's.
I think the previous generation 3 series and 5 series have ever lasting style also – but would vote against the Ms, which sometimes have too much body cladding for me.
Aston Martin is a no brainer choice.
To pick two “lesser” cars which haven’t been mentioned:
A MK4 VW Golf – I think that was the purest version of the classic hatchback shape.
And the 2nd generation Mazda MX6 – just really well executed coupe.