Ford GT40 Mk.I vs Mk.II vs Mk.III vs Mk.IV vs Matech Ford GT; GT40 Mk.I, nothings beats the original to me.
Porsche 911 GT1 Street (996) '97 vs Mercedes-Benz CLK GTR Street vs Lotus Elise GT1; Mercedes-Benz CLK GTR, I just love that thing.
Porsche 911 GT1s; I think I'll pick the 1996 993 GT1, I've always preferred the looks of the 993 over the 996 and the GT1 model is no exception to this.
BMW M3 (e30) vs Mercedes-Benz 190E Evolution II; BMW M3 as I most of the time prefer BMWs over Audi and Mercedes.
Steeda Q 351 W Mustang vs Saleen S351 Mustang; Saleen, I always go with the Saleen Mustangs.
2015 Chevrolet Corvette Z06 (C7) vs 2015 Nissan GT-R (R35); Corvette Z06! The C7 so far just plain rules in my opinion, especially the Z06. While the Nissan GT-R just wouldn't be as fun or challenging to drive I would imagine, and I just don't see much of a soul in it.
Random Muscle Cars; The 1969 Dodge Charger Daytona is my pick, it just sounds like the best performer out of them all.
Random Cars; Subaru Impreza Outback Wagon, it's the best looking to me and seems to be the best balance of fun and practicality of all 5 of those cars.
Classic Boss 302 Racer vs Modern Boss 302 Racer; I think I'll go with the classic. The original Trans AM Mustangs were legends I think.