The Good:
I haven't seen anyone mention Michael Moorcock. Nearly all of his stuff is excellent. I particularly recommend the Elric Saga, and Corum series. The Hawkmoon and Erekose books are also good, but they both tend to get a bit whiny at times, particularly Erekose. The Second Ether books are also superb, but a bit difficult reading at times, since they jump back and forth between the main narrative, and a bizarre, somewhat surrealist secondary narrative connected to the main thread in rather odd ways. Dancers at the End of Time is extremely strange, and doesn't really fit into either sci-fi or fantasy. Von Bek is pretty standard fantasy, but well-written; and Nomad of the Time Streams is sort of proto-steampunk.
L.E. Modessitt's Saga of Recluce is one of the best written fantasy series' I've encountered. Some people findit repetitive, and he does tend to write fairly similar characters and stories; but this only really applies to about 3 or 4 books, and all of them have significant variations. The character types are similar, but the characters themselves are well-developed individuals, and each reacts to circumstances in his own way. And he does explore some vastly different character types and situations in most of the books. One caveat, despite what anyone else tells you, the series is best read in publication order, not in chronological order, for various reasons.
Stephen Donaldson has some good work as well. The Chronicles of Thomas Covenant have already been mentioned, and derided. I think the main reason people don't like this work is that Covenant isn't a Hero, nor is he a standard Anti-Hero; and is very difficult to sympathize or identify with at first. The books are very dark, and take some effort to read, but are well worth perusing. Mordant's Need is a much shorter series, but lighter and more traditional fantasy than Covenant. Although it's not fantasy, I'll also mention the Gap Cycle. It's essentially a sci-fi interpretation of Wagner's Ring Cycle; and while unrelentingly dark and grim, is also very well written.
Louise Cooper's Mirage is highly recommended. The Time Master trilogy is formula fantasy, but quite good at it. The Chaos Gate sequel, and Star Shadow prequel trilogies are not as good, but still worth reading. Avoid the Indigo books.
The Not-So-Good:
Piers Anthony's fantasy and space opera are kind of hit and miss. Xanth is okay at first, but quickly degenerates into pure unadulterated crap. The Mode books are inconsistant, and indulge some of Anthony's rather odd fetishes; as well as his highly prevalent rape fetish. Cluster tends to combine some of the worst aspects of old-school space opera; although I have to mention that he does a very good job of creating a completely alien mode of sexual reproduction, and then finding a way to work a rape scene out of it. Geodessey is ludicirous. Incarnations of Immortality has some interesting moments, but is inconsistent. The books I would recommend are Cthon and its sequel [/i]Phthor[/i], although technically they're space opera; the Battle Circle trilogy, and the Of Man and Manta trilogy, which is also space opera. I should mention that all of Anthony's works, with the exception of Xanth and Of Man and Manta, you're going to be subject to multiple, often highly graphic, rape or attempted rape scenes. Bio of a Space Tyrant is the worst for graphic and violent; while Pornucopia consists of little else, played for humour.
David Eddings is grossly overrated. His plots are formulaic with gaping holes; his characters are flat, trite, and frequently carry the idiot ball.
Robert Jordan is also badly overrated. His books are full of pointless filler; his characters are all idiots, relationships are all bad stereotypes, and he spends a lot of time ripping off other, better work.
Terry Goodkind is to be avoided like the plague. Unless you like poorly written Objectivist screeds disguised as fantasy novels. Seriously, the guy badly wants to be Ayn Rand; but is nowhere near as talented. I read up through Faith of the Fallen (which is pretty much just a re-write of The Fountainhead out of sheer trainwreck fascination before nausea prevented me from continuing.
Saberhagen's Lost Swords books read like they were written for by Jr. High Schoolers.
So, Best Served Cold is the sequel and ending, then? I thought it was a standalone novel set in the same world but not a part of the First Law trilogy...
