Get all the above in a 16M.
Nice try Doug but a V12 in front is very very different to a V8 in the back (unless you only do dragstrips).
Rangerat1 - you need to go and drive these cars, as it is impossible to say what you should go for. All are very different to drive and which one is best for you depends on how you are going to use it, and what your preferences are.
For instance, I would never buy the Barchetta as my first Ferrari as it is quite limited in its use. It is a glorious car, but I wouldn't want to do a two-week road trip in it like I tend to do in my other Ferraris. The Scuderia is absolutely wonderful and of the three probably my favourite for a first Ferrari. The manual gearbox doesn't work so well in the last incarnation of the V8's, IMHO. It is hard to keep up with the engine when you're pushing on a twisty road.
I love manuals but I am glad my 458 doesn't have one. For the 430, I'd probably feel the same. But then, if you have a more cruising driving style, then it could be the perfect choice. It is gives a wonderful tactile sense and you feel more closely connected to the machine.
So - as I said - drive them, and make up your own mind. Best of luck! All three are wonderful, you can't go wrong really.
[EDIT] Sorry - didn't see your comment that it's going to be second to an MP4. In that case, I would probably go for the Barchetta as it is so, so very different to the McLaren. It's manual, V12, top down, more relaxed driving philosophy but still pretty darn quick. A nice counterpoint to the Mac. Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!