Carl Sagan popularized astronomy for the masses more so than Neil DeGrasse Tyson. I have never even heard of Tyson, so for me Carl Sagan is the most influential in the field of astronomy. His works have influenced generations of people about the science. Perhaps Tyson is the next person in line to change the way astronomy is viewed by the people.
I think Carl Sagan better popularized astronomy for the masses. I think he managed to be a little more before his time then Neil Degrasse Tyson was. This gave him a better lead and he was able to influence more people around him as he traveled. Will it stay like that maybe not.
I think Carl Sagan did a much better job popularizing astronomy than Neil DeGrasse Tyson. Look at it this way: Sagan's TV series Cosmos was eagerly watched by my generation, and we still remember it fondly today, still quoting his catchphrases, "Billiions and billions..." and "we are all made of starstuff." Tyson doesn't hold that same place in people's imaginations or affections.
Tyson is remaking Cosmos with updated special effects. That shows you which one is the original and which one is the follower. And although both men have very healthy egos, Tyson really seems like a smug egotist.
Sagan has a memorial on Mars. I don't think Tyson will be getting one.
As Carl Sagan is one of my favorite astronomers, and his influence was very great in the world, I would have to say that he made astronomy much more popular. He gave people the light they needed and helped to explain the complex things about the universe that we couldn't understand.
Everyone does what he or she can do in their own time and place. Tyson gives much credit to Carl Sagan for inspiring him to delve into the world of astronomy. So Carl Sagan was the first to popularize it, although it has to be said that in our time right now Tyson is doing a great job.