I've just seen two incredible £1,000,000 Porsches

[Racer Boy]

I'd pick the 918. Once you start driving the 964, then most of it's appeal (at least from a value standpoint) gets lost.

Also, selling the 918 would be easier, so I'd immediately sell it and buy an bunch of other cars that I've always wanted. 1,000,000 pounds would buy some nice cars!