Oh, wow... tough question this time. There are SO MANY black rifle accessories moving across my bench each year. Even narrowing to this month would be tough!
If I had to stick to just one though, it would have to be the new line of Eotech EXPS/XPS sights. Not because the Aimpoint T1 is any better or lesser a sight, but it is very compact and doesn't have the FOV as the Eotechs. I have tried and owned both sights, I have kept the Eotech XPS. The XPS is newer tech and for me personally, is easier to use and shoot good scores with.
The Eotech sights have sometimes been much maligned over the years, primarily because many of the 55X series sights that take AA batteries would turn themselves off under recoil. The new XPS sights solve this by having a (better) CR123 battery mounted transverse to the upper. This negates the effects of recoil impulse on the battery compacts and makes the sight almost half as long. It also can now be mounted out over the railed hanguard, allowing room for both a magnifier and BUIS - another oft-mentioned shortcoming of the 55X series.
Light, excellent FOV, longer battery life, improved reliability, less demand for real estate on the upper and no need to buy an expensive ADM or Larue mount to co-witness with your irons. In other words, I have to give this a thumbs-up as my favourite new black rifle accessory for this year.
Close seconds awarded to Canadian-made pistol-length barrels (thanks NEA for making other options besides $500+ 7.5" Lothar Walther barrels from Questar) and the Spex series of muzzle devices going back into production.
And since you asked for eye candy...
My theoretical future vote goes to the new Troy Industries AR15 ambi charging handle. Unfortunately, I've not seen it in Canada yet and have not tried it personally, but it looks like it will be a winner, especially if they offer extended tac-latch options in both left and right. I'm liking Troy Ind stuff more and more each year - maybe my new favourite US-based AR company. They have become the "go to" for me when it comes to ambi accessories and FF rails.