When I went to Vegas last time, I drove 4 cars at Exotics Racing. The R8 was my favorite over the Nissan GTR, Corvette Z06, and Ferrari 430. Then I did a 100-mile rental of an R8 to see how it drove on various roads. After that, I was sold. It was around $1700 total, but that was money well spent. Much cheaper than buying the wrong car and dumping it after a few months.
When I started out, I was leaning towards the 430. The R8 was just a better all around car for the same price, and a manual didn't cost a premium. This time, I'm expecting to prefer the 570S over the 458. The AMG GTR is a completely different car, so that's going to be interesting.