I haven't read many of these and have heard of even fewer, so I only voted for one thing and that was an F for Stephen Lawhead's Pendragon Cycle. I loved these books as a young teen, however, do be aware that they are from a Christian publisher and thus have some weird "the good guys are/became Christians and that led the way to victory" type stuff in them. Because it's been like 25 years since I read them, I don't remember much other than loving them at the time, so I don't know how I would feel reading them now. If the Christianism isn't too intrusive, they might still be enjoyable, so I think they at least deserve a try.