Haven't read Dunsany (yet), but I'm quite a fan of Sanderson, and it's really clear how much writing has changed in recent years. I'm not someone who "sees" the things they read, but Sanderson's novels really do feel like a movie with more details.

OP, I think you kind of miss the point here... Close to none of the classics we know would be published today, you can't judge a book by this factor. Besides, it very much is about whether you enjoyed it or not. You don't really criticize the book in your post: you name subjective things you didn't like (boring prose, unintrestting characters, lack of proper pacing), then proceed to declare that Foundation is not a classic. None of us have the right to say that in general, even less so if your points are not concrete (aside from the pacing, I'll admit it is a bit weird). Finally, why were you expecting the author to cut right to the meat, as you said? As far as I can tell, books have only recently started to become so fast-paced. Not to say that all stories prior to the 21st century are snore fests; I think they simply have a (mostly) different style.

I'd suggest Dune by Frank Herbert