Note: a "novelette" is an odd, old-fashioned term, referring to a work with a length between 7500 and 17,500 words. A reallllly long short story, I suppose, as opposed to the novella, which in today's terms (what with brick-sized doorstoppers and all) constitutes a very short novel.
"The Secret Life of Bots," Suzanne Palmer, Clarkesworld Magazine September 2017. (I've never heard of this writer before, but obviously I need to seek out her work. This story was a delight from start to finish. This is the tale of a tiny repair bot, reactivated after a long sleep aboard a ship previously consigned to the scrap heap. The ship is the only thing standing in the way of a massive Earth invasion force, and it needs all of its bots to fix it up long enough to stop the aliens. This story is funny, poignant, whimsical and altogether wonderful.)
"Children of Thorns, Children of Water," Aliette de Bodard, Uncanny Magazine July/August 2017. (This story apparently takes place in the author's Binding Thorns universe, which I have not read. Nor am I very likely to, based on this sample. I've heard people raving about it, but this tale of magic, Fallen angels and cooking just isn't my thing at all.)
"Small Changes Over Long Periods of Time," K.M. Szpara, Uncanny Magazine May/June 2017. (This odd tale of a gay transgender vampire definitely isn't my thing, either.)
"Wind Will Rove," Sarah Pinsker, Asimov's Science Fiction September/October 2017. (This story took me by surprise. I'd thought there was nothing more to say about the SF cliche of a generation ship, and Sarah Pinsker comes along and proves me wrong. This is a lovely, poignant tale of history, and art and music and beauty, and how the stories we tell each other are passed along to the next generation, for better or worse.)
"Extracurricular Activities," Yoon Ha Lee, Tor.com 2/15/17. (This is set in Lee's "Machineries of Empire" universe--the books are Ninefox Gambit, Raven Stratagem, and the forthcoming Revenant Gun, and you should be reading them right now--and features Shuos Jedao, later to be an infamous undead General. This story of an undercover agent extracting a traitor is smaller, more intimate and whimsical than the full-blown novels, and even laugh-out-loud funny.)
"A Series of Steaks," Vina Jie-Min Prasad, Clarkesworld Magazine January 2017. (In a future where food and organs can be printed, this is a caper tale of a woman blackmailed into doing one last forgery, and her revenge. The ending is especially poetic.)
Wow. This one's going to be hard. At the moment, Suzanne Palmer has the slightest of edges over Yoon Ha Lee, Sarah Pinsker and Vina Jie-Min Prasad, but I think it's basically going to come down to a coin toss, and how I feel on the last day of voting. The top stories have already been reprinted in various "best-of" collections, showing the quality in this category. Check them out and see if you don't agree.