I admit that I've had only two real cartoon crushes: Lisa Simpson when I was younger, and Meg Griffin from Family Guy when the series started. Other than that, I've never really had any crushes on cartoon characters.
As for falling in love with cartoon characters versus humans, I'm neutral. As far as I'm concerned, true romantic love doesn't really exist, except as a chemical reaction in the brain that fires off, and is used as a code word to "sanitize" what could seem to simply be the uncouth idea of propigation of the species, by convincing people there's such a thing as "romantic" love.
I believe in love in general, but I remained unconvinced that there's such a thing as true, or "romantic" love.