I know who Mandela is and realize the huge, huge impact his death has on history and what a great man he was and what he did for the world. That said. I think I "miss" Walker more since his life had "more of an impact" on mine in the form of the entertainment I got from the F&F movies. The world is impacted more by Mandela's death but we could argue Walker's death was "more tragic." Mandela lived an amazing, rich, long life that impacted many and died an old man in his 90s. Walker was a young man who died in a tragic accident with still more than half of his life ahead of him.
Two very different types of deaths and two deaths that mean very different things. But, really, years from now only one of these deaths will be remembered in the history books so that's what really counts.
It's unfair to compare the two.