I faced this dilemma just recently after I wrote off my 350z (04) in the wet on the highway. I had a roadster, I hated the chassis flex, so I'm going to get a more ridged body shell.
I was really considering 370z for it's more refined designed and excellence in performance in terms of an NA. 370z no doubt looked more modern, but I dislike the fact that it has only has two seats, and relatively heavy for that matter. And I considered the fact it is rear wheel drive, it would be better if it is all wheel to put that power down to use on normal street tired, especially in the wet. It is a street car after all.
So I went for a R34 V spec II, 4 seat, all wheel drive. It drives well for its age. Only thing I found to my dislike at the moment is that I miss that low end torque of the VQ engine when claiming the hill in high gears.
Happy hunting!