realistically -
Id go with the GT3
I dont like the looks of the F40 - if I needed one of those Id go with the 288GTO - MUCH better looking and more rare.
And the SLR . . .Id rather have a CLKDTM or whatever they are calling the new one. Cheaper than the SLR and faster too - also more rare.
The GT3 is just sick for a porsche - the faster narrow body and the 9000rpm Ti conrod motor