Which should I use: 'mediums,' 'media,' or 'channels'? I've correctly used 'wilfully promote' in the sentence, haven't I?

Which should I use: 'mediums,' 'media,' or 'channels'? I've correctly used 'wilfully promote' in the sentence, haven't I?

Cell phones, e-mail, and social networking sites are (mediums, media, channels) through which one can wilfully promote hatred against one's/his fellow beings.