I'd have to say 2Pac. I still remember where I was and what I was doing when they pronounced him dead. His death didn't impact me because he was a great rapper...his death impacted me because of the person he was, and the things he stood for. Most people don't realize that 2Pac was on a different level than most. He said shit that made the world think, and that's why there are 2Pac murals around the world...and people wearing t-shirts bearing his image from Brazil to the deepest parts of Africa and Australia. If that's not power and respect, I don't know what is.
As far as his music goes...All Eyez On Me was released less than a month before the death of my best friend. LIFE GOES ON made me sit and think about my dude...2Pac's words made me sit and think about my dude...and some of the shit he said actually helped me cope with what I was going through. So to have the man that felt my pain pass away 6 months later, it actually fucked with me a bit. 'Pac is the reason I don't keep my mouth shut...it might not be wise at times, but he made me realize you gotta keep speaking your mind if you want people to pay attention.