As far as white rappers, there's not a ton that I love. I'll attach a couple songs. They may not be their best work, but these are a few standouts. Evidence is my favorite. He's mixed, so maybe he's not entirely white.
A lot of people liked Action Bronson. Not sure how he's been doing since that Ghostface situation. I always liked 9th Wonder's old proteges Joe Scudda, Sean Boog, and Thee Tom Hardy all were/are pretty dope. Those 3 aren't really doing music anymore besides Tom Hardy. I don't listen to many others. Some people like that guy Apathy. I've heard a few dope songs from him. Ill Bill and RA the Rugged Man used to have a lot of fans back in the day. That guy from Jedi Mind Tricks I never really liked, but some people do...Vinnie Paz (sp?)
EDIT: Wait, is Brother Ali actually white? I'm seeing him listed here a few places. I thought he was just albino?