Personally, I know good girls are better all the way around. Many times they turn out to be the biggest freaks because they've bottled up all of their sexuality and when you tap into it it's like breaking the flood gates and all of that pent up energy just explodes on my dick. Good girls tend to have that fire in their eyes, an intelligence that makes them truly sexy, not just going through the motions, but really feeling it. Being a good girl doesn't mean she's not kinky, and they're usually much more mature and more stable emotionally, much better relationship material if that develops, or god forbid the contraception fails and she gets pregnant.
Bad girls tend to be burn outs full of emotional baggage who generally f*** up other areas in your life if they stick around for any length of time, typically dull, typically don't have much in the way of character, morals, standards, self control, self worth, and you run a greater risk of aquiring STD's. Leave the skanks and sluts for the guys who can't do any, or don't deserve any better.