Im partial to the s2000 myself. Its a car you can leave stock and still have a huge grin on your face every time you drive it. The 350 also looks like ass as a convertable. The VQ is an awesome motor, but the rest of the 350 has been problem prone (as with almost every other nissan :/ ). The high revving s2k gets my vote, but to be honest you really need to sit in and drive both to see which one you like better.
I personally fit great in the s2k, but I just feel cramped in the 350. Kind of weird, but its just how I fit.
(and wow its been a long time since I've been here)
Oh, and with the G35. i've always thought they were awesome pin pics until I sat in one. Just not that impressive to me. And over at s2ki.com there are a lot of people who have switched over that feel the same way as reechy.