So much 300ZX hate...
*Waits for 300ZX guys to come into discussion*
But I'd either pic a R32 or 180SX over the 300ZX as I would go for a 240Z / 260Z / 280ZX.
S Chassis (180SX / S13 / S14 / S15's) are fun to drive, due to it being a light car, has the power and can be tail happy.
I'd been in a few 180SX with about 250+ kW's = fcuken mad and I drove a S15, fun in the wet and easy car to drive.
R32 GTS-T, just adds to the fun with the extra 2 cylinders but have only been in one as I already drive a R32 GTR.
I'd guess it comes down to what car your prefer the look of, or what characteristics of both cars you like and choose.