So fantasy:
Adrian Tchaikovsky - Brilliant. It's a Kinden Surprise (aha, aha, ah. No? mmm, fewer Kinden puns then I guess)
Pratchett, of course, and really looking forward to the new Watch series coming out on the small screen.
The Fionovar Tapestry Trilogy. So overlooked, but a delight to read. So emotionally well written that as a survivor, I've only ever been able to read sections of the end of the first book once.
N K Jemisin who's works are mind-blowing. . .1/?
...as are Robin Hobb's.
Elizabeth Haydon's Rhapsody books also hit the spot with me. Suitably myffic, and grand in scale. Love them.
Brandon Sanderson. Excellent. I've watched him improve leaps and bounds as a writer and I'm so impressed, especially with what is promising to be a truly epic-in-scale series, The Stormlight Archives.
...2/?
Mathematician's answer. Yes.
The first three books stand so well as a trilogy in their own right and they do stand above the other books in the series as well, but I still like the other five books even though there is a noticeable drop in quality.
@SakuraNoSeirei I've only read the first three books, so I can't comment on the quality of the others. I knew there were more, but never got around to reading them.
Likewise with Sanderson. I haven't gotten around to reading Oathbringer yet, and I'm not sure I will unless I end up getting a copy for free at the 2018 World Fantasy Convention. (I'm not a fan for various reasons.)