This is a really interesting question. probably Curt Swan. I had been getting Superman and all related titles since I was around 8 very regularly until I was around 18 and he drew them for 8 of those years. That’s the vast bulk of my comic collection as he was drawing around 2 per month and I also went back and got most of the back issues from when I was around 2.
Writer-wise, that means Cary Bates is probably my top man. I wasn’t really a Marvel guy and only really knew the 60s stuff, which I loved, but picked up in reprint pocket-books in the 80s. So I have a lot of Stan too, but only maybe the first 30 issues of the big characters as the books were discontinued after 3-4 years.
I have everything Moore and Miller have ever written, but in terms if quantity I guess it would be Bates, Swan, Stan and maybe Gerry Conway (who’s so underrated, his Batman and JLA with Perez in particular).