- Secondary World, not alternate reality or real world with fantasy elements
- Assumed adult audience (not YA)
- Epic scope
- Length (the trilogy as the kind of "minimum" seems to be the trend—no doubt thanks to Tolkien.)
- Multiple perspective point of view characters.
This does narrow it down considerably; whereas Poul Anderson's Three Hearts and Three Lions is High Fantasy, it fails to be epic because it's not that long (less than 200 pages) and only has a single point of view character (Holger Carlson.) Also; given that Holger is a real world character in a semi-fictional world, it falters a bit on the first point as well.
Curiously, with this highly constrained definition, there aren't really that many works of note that qualify. This led to, as you'll see if you follow the link, the notion that a lot of authors who are generally considered hacks by fans at large getting surprisingly high rankings. Of course, his opinion of who is or isn't a hack may differ from mine or yours, but the point is that finding authors who's work qualifies is relatively difficult, actually.
I'm not going to attempt to make a list, because I've not read many of the guys in the field, or I've given up in disgust on several (Brooks, Goodkind, Donaldson, Erikson, Martin, Abercrombie, Jordan, etc.—although often for different reasons. He also doesn't list Phillip Pullman, but I gave up on his works in disgust too.)
I will say, though—I'm not necessarily surprised that David Eddings was rated fairly highly. He did kind of become a parody of himself after a while, but the original Belgariad series is still a fun read, and pretty masterfully constructed. Donaldson I could never get very into, mostly because the most significant point of view character, Thomas Covenant himself, was such an unlikable douche-bag that I hated it. Even he admits that he ranked it highly more because it was a difficult work to pull off rather than because he necessarily liked it. I'm a little less inclined to be charitable on the merits of books that I dislike. I'm glad to see Raymond Feist getting some love; the original first few books, before it dragged out into self-parody again, plus unlikable characters who reflect the non-values of liberals and bohemians start to become all too common after a while (why is it that so many modern writers are so contemptuous of actual heroes, anyway?)
I also think the original Dragonlance Chronicles merit a place. They're actually not bad, and they were supremely influential. He actually calls the Legends trilogy even better, but I never read that one. Maybe I should? Someone asked why, if he's going to include that one, he doesn't have the Salvatore Driz'zt stuff, which is a valid question, I think. It is, by that definition, also epic fantasy.
For that matter, in the world of shared world spec fiction, there's a lot more examples. There are epic fantasy cycles within the Black Library corpus, and elsewhere in the D&D or Pathfinder corpus—although often the scope fails to rise to the occasion, I presume. Mike Lee's Nagash Trilogy, and the whole End Times project (which is admittedly written by multiple authors) qualify as well. (I really need to finish reading those...)
Anyway, I find that I'm giving some thought to this concept. Epic Fantasy may be among the most difficult fiction to write, because you have to write a lot of it for it to count, you've got to juggle lots of plot threads and lots of point of view characters, etc. It's no wonder that not very many people do it well. Even the successful guys who sell tons of books (Robert Jordan, George "Rape Rape" Martin) tend to drop the ball.
I've also found myself wondering if Steven Erikson was ever able to sort out his crippling flaws as a writer and make anything of the Malazan Book of the Fallen series.
Anyway, yeah—this is kind of a rambly post, referencing someone else's post. Not the best of material. Hey, not every post can be a winner. This one is what we call a punt. I've been given something to think about, because I've been avoiding epic fantasy, mostly, for some time. Maybe I should give more of it a try.
As a totally separate aside; I did fairly recently read A Throne of Bones, the first book in the epic fantasy series by Vox Day himself. He's right, even if it is just him saying so. It's quite good. I picked up the second book while it was free briefly a month or so ago, but I'm not going to attempt to read it until it's actually the complete version of the book. I think the update to the Kindle file is due late in the year.