I haven't even read this thread until now... just because the subject seemed so weird. "Racism movies" has never seemed like a defined sub-genre to me.
People being cruel to each other [outside the consequence-free context of a mindless action movie] is generally depressing - so no, I wouldn't say I like them. But there have been good ones, obviously.
I'm partial to big-scale biopics, so I guess I'd choose
Gandhi as my favorite. [The thread starter will probably endorse that.
]
Glory was pretty impressive too - though I don't know if I'd want to watch it again.
As a Jew, I suppose I'm duty-bound to include a Holocaust picture in here somewhere.
The Pianist was quite good - though it pains me to endorse the product of a child-molester.