This is an interesting question to me, because I have been toying with similar ideas: GT40, F355 berlinetta, 996 911 Turbo (OK, so not really the GT3). If you look around, all three can actually be had for similar money. The Porsche is definitely the most advanced, with AWD and stability control. It is also easier to drive fast (good for a novice like me). The Ferrari has a mystique that is hard to explain, and is not necessarily backed by quality or reliability. The GT40 has the looks, the sound, and can be set up to do what you want it to. For me, I am interested in the driving experience more than the fastest lap time, but I do want a car I can track regularly.
I think the GT40 is the best all-around package: it looks fantastic, it sounds fantastic, it can be plenty fast. Plus, it's reliable and you can maintain it yourself. The Porsche TO ME (and I say that because they are fabulous cars) is just not as inspiring. The 355 is a car I have lusted after for years, though repairs and maintenance are serious matters. The GT40 is the best looking sports car ever made. The only problem I am having with it are the fuel tanks, which I can't get out of my head. There is something about running along with 10 gallons of gas as a side impact beam that has been giving me pause (if someone would convince me that this is not a concern, I would greatly appreciate it...)