I would have gone for Mandela in the leaders category,
On balance, I think I agree with you. It's clear he did a magnificent job as South Africa's first democratically elected leader, and events since and elsewhere have shown just how good he was.
and Ali in the sports category was easy.
I really don't get that. Everybody assumes he was the greatest just because he said so.
For the activists, don't have a problem with MLK but might have gone for Ghandi.
Agreed
For scientists are, I'm with jeremyp and would have gone for Einstein.
Obviously!
The entertainers, of the choice avaiable, Chaplin, but thought Elvis should have been in there. I am a huge Bowie fan but not sure the global impact is as wide.
Of the choices there, I would go for Bowie.
The explorers category is just odd, but Shackleton seems bizarre. Of the choice there, Armstrong.
Shackleton because he was a proper explorer and when everything went wrong, he made an almost super human effort to rescue his crew. Armstrong was just the point man in a huge team effort. Had it not been for Gus Grissom's death in the Apollo 1 fire, it's likely few people would know who Neil Armstrong was.
The artists category, yet to be voted on seems a bit of a motley. Given a free vote, I would likely have chosen Dali. Of the four already chosen, Picasso.
I think Picasso is the outstanding artist of the 20th century.