Not sure quite what ‘classic fantasy’ is, tbh. I’ve played a lot of what I think of ‘vanilla’ D&D fantasy, which has become its own thing. Elves, Dwarves, Halflings etc per D&D aren’t really what I ever read about or look for in actual fantasy fiction. At least not these days. When I started with 1e I found that D&D could easily be used to adapt fantasy from other sources. Less so later. IMO, of course.
I assume Dark Fantasy is more along the lines of the Old World of WFRP 1e etc, or books like The Black Company, or Jonathan Strange & Mr Norrell. Some of Michael Moorcock’s fantasy fits in here, to my mind.
I prefer fantasy to be firmly based off mythology/folklore, or someone’s own homebrew adaptation of some books/films/TV. I prefer relatively low magic, and grittier games. I like the three instances I gave above, for example. However, I don’t tend to like things being excessively grim or dark. I’m also quite happy for the fantasy world not to have Elves/Dwarves/Halflings or any of the familiar fantasy races.
However, I’ve been around a while, so I’ve learned to enjoy a variety of fantasy styles, and to enjoy having the variety. Which is probably why I enjoy playing in the more high magic/higher fantasy 5e and GURPS games in one group, but in the other group (where I’m the forever GM) I run low magic/low fantasy worlds via Into the Odd & Tales of Argosa.