I have driven half of those and the Ferrari's are AMAZING.
The F430 is a sweet ride and you can get them for less money. Try one and see if you agree - They are worth it!
The Audi R8 is BOORING - It feels like a rent-a-car unless you have your foot in it. Too small, too civilized.
Lambo Gallardo - Sweet sounds - sweet ride. Get one if you can't get the F430. Avoid the carbon brakes unless you autocross a lot. They are like anchors once they warm up. They go from normal brakes to very agressive when warm and nothing in between. Not a fun street setup in my opinion.
The Maserati GT is a DOG to try to drive hard. Not much under the hood. You do get some excusivity and style but not much else. Too much "touring" in the grand touring if you get my drift.
The Ford GT is an uncomfotable car to get in and out of. It feels great at speed but it lives like a thinly disguised race car. Like a track only car with lights and turn signals. Shifter sucks big time but it is otherwise very driveable. So much torque you almost don't need to shift.
For my money - get the older Ferrari and pay $$$ for the maintenence. If you save driving it for just the special sunny days, it should not be too bad. It makes you think you are a better driver than you actually are.
Google "Wold Class Driving" and start saving your pennies.
-Mark.