racerx:
Jean:
Although Aston V8 sounds glorious, I thought the V8 lacked a bit of a punch.
The sound accelerated faster than the car.
I'm sure you will see what I mean if you test drive the car.
I think the opposite can be true of the 997S.
for 2009 models
I see times quoted as 997 - base 4.7 ; S 4.5 ; pdk 4.3 ; Targa 5.0
Aston V8 4.7
for previous years add some time because both have improved. So to diss the Aston as some kind of bark worse than bite ride is not valid. (these numbers make my 25 yo classic quite happy) All those times were achieved with people beating the crap out of the mechanicals, something you should not do on a regular basis to a car you intend to keep. Add in the fact that the human body will not be able to percieve these little differences and you see just how silly these numbers are.
I have accelerated in a stradale flat out many times, it is quoted at 4.0 and my car based on runs is a 5.3 and yet mine feels faster to me because of sound and initial grunt. So that is why I say buy a car you like and forget the numbers.
To Elijah;
Looks, sound, and comfort are the biggest considerations. Since you added the Maser GT to the list, I would put that into a tie with the AM V8. NIce video on here in a thread about it.
Good Luck, big decision.
racerx,
You are correct. The AMV8 I've owned is 2007 model, so the new version might have improved in acceleration.
However, I was talking purely in terms of the seat of the pants feel.
Aston's long final gear made me feel that the car was going slower than the sound. I loved the growls everytime I stepped on the gas, but when I looked at the speedo after a long acceleration I was still doing less than 100mph. 
Perhaps it's better this way to keep the speeding fines to a minimum.
I still think R8 is a better choice out of those three.