Both of them are just as bad but I'm going to say racism is worse because the colour of your skin is something you can physically see whereas you don't have to reveal your sexuality.
So if there's like a holocaust against homosexual people unless you openly say you're gay or **** someone of the same sex in public, you're safe. Whereas the Jews couldn't be like "what? Jew? I'm not a Jew what makes you think I'm a Jew?!"