I've have seen black people using 'Nigga' in a derogatory manner. I won't argue that 'Nigger' is used worse but I don't think anyone respects either of them. 'Nigger', 'Faggot', 'Kike', 'Chink' and like words have no respect in them and do not convey anything positive, regardless of context or variation. However, I don't believe we should ban someone for simply using them. I feel like a simple infraction gets the point across, and if they repeat the offence, especially against the same victim, then they should get banned for not learning their lesson.

Below is proof of 'Nigga' being used in a derogatory manner. Has heavy use of profanity, but I just know someone would argue that 'Nigga' can't be use aggressively or derogatorily.
https://www.youtube.com/watch?v=Zhgwy9y5ttA