I think it is not hard to understand that racism and homophobia are evils.
There are the ones who consider that both are equal evils. There are the ones who agree that both are evil, but consider that racism is worse.
We hear sometimes "I tolerate gays, but we should respect the ones who have different opinion". But we seldom hear "I tolerate blacks, but we should respect the ones who have different opinion". Maybe there is a belief that disliking homosexuals is OK because choices like sexual orientation, religion and political views can be cricticized. But the color of the skin is not a choice. This is a misleading view, considering that sexual orientation is not a choice too.
This is mostly used in cases of gay marriage, which one can argue that a person can oppose gay marriage without being entirely homophobic. Rarely do people think gay people should be treated as an inferior people (as was the case with black people pre-1950's). But to answer the question, I would say racism is worse, because you can tell someone's skin color pretty easily, whereas you have no idea about sexual orientation unless the person told you or are giving obvious clues (holding hands with the same sex, etc.). This makes the discrimination easier with race. Plus sexual orientation is a lot more complicated to understand, a person's race is literally just their appearance.
The homosexual lifestyle is definitely a choice. Homosexuals choose to engage in sexual relations with each other, go to gay bars, march in gay pride parades, etc.
Question: Did you choose to just be attracted to girls one day? Did you just wake up one day and think to yourself 'I'm going to fall in love with this beautiful girl today'?
