While I've only played Call of Cthulhu once, it was definitely memorable Nothing like playing in a shadowy room, at the witching hour, when something literally goes bump in the night at a dramatic time, it scared the crap out of us.
I play d20 system because it's the most popular system, I do enjoy other systems a lot, especially skill based systems. I've played RuneQuest, ElfQuest, BattleLords, Call of Cthulhu and many other skill based systems. Unfortunately I had to get rid of some of my old games about a decade ago, ElfQuest was one of them. One of the problems with those games was my friends didn't play those games.
I've read all of Lovecraft's Cthulhu tales, because of role-playing. I've read the original Conan, John Carter of Mars, and other classics. I read Fritz Leiber's Fahfrd & Grey Mouser stories, and other classics when I was younger. I doubt I would have ever read those classics were it not for Role-playing.