Contrary to popular belief, not ALL girls go for jerks. All of my most rewarding relationships have come from guys that I was friends with first.
And this isn't just a one time phenomenon.
Many girls would rather date guys that they can be themselves around, guys that have already seen them at their worst, and still stick beside them.
I will agree with AppleZoom on a few issues though.
It is important that a guy voice his opinion, no matter how contrasting it is to the girl's. However, I wouldn't go so far as to say a female president would be moody, or retarded children just take up space. You do still want the girl to enjoy being around you, don't you? I can't speak for everyone, but a guy who would have ideals like these is not the kind of guy that i would want to associate with - in any manner.
Debating a girl's opinion can be fun and show that you are confident. But just remember to be yourself while doing it. Don't defend things that you don't believe in just to have something to argue about.
And in the end, if you end up being a friend instead of a date, don't be too disapointed. You'll be the one that she's coming to when she's upset, or when she has good news to share. As your friendship gets stronger, she may begin to see that the jerks that she is dating will never compare to the great guys that are always there for her.