Regular street cars. I'd choose a Dodge Viper GTS, 1969 & 2010 Camaro SS, 2007 Mustang Mach 1 '71 and the V8 GT Coupe '07, Volkswagen Golf IV GTI '01, DMC DeLorean S2 '04, etc over any race car or super car.
Sure those race cars and super cars are fast, and handle better most of the time, but to me speed isn't everything. I'd much rather win a race with a car that is out of the norm. Like using the DMC DeLorean fully upgraded to beat the Supercar Festival or Gran Turismo World Championships A-Spec races(true story, btw.....)
Stock or upgraded, I just prefer the regular street cars, mainly American. I like using some of the cars I see on the road in real life, as well as some of the American cars and some other countries' regular street cars I would dream of just driving once in my life... Like a Ferrari, Lamborghini, Viper GTS Coupe, 1969 Camaro SS, Dodge Charger R/T '70, Ford GT40, etc...