I mean, for the world as a whole, probably not much would change, it would just be minus a pretty large fandom. For specific individual people, it could make more of a difference- like for me personally, I do think Doctor Who has made a difference in my life in a lot of ways, and I think I'd be different, to some extent or another, if it had never existed. Probably not in a good way. I don't know, though, maybe I'm just a weirdo who takes fictional stories too seriously lol.
Really difficult question for me, I've loved all of them. Simm is my personal favorite though, followed by Delgado, Gomez, and Jacobi (in no particular order between those three), and Dhawan and Ainley kinda tied after that.
My personal favorite is This Is Gallifrey