Holy crap, yeah. I remember just entering the area... Hearing those wings beat... Makes you feel like an ant in comparison.

It's the scream that got me. Loud screech which wasn't like usual 'roars' in fiction. Plus the way it moved, reacted to where you were attacking it.

And since this game has no easy mode(coop and extensive statbuffing) we might this time get very prepared to die. :p

Oh man, between Souls III and Bloodborne alone, it would be hard to pick just one. I would have to go with:

-The King of Storms/Endless King (Dark Souls III): One of the most epic boss fights, period!
-Shadows of Yharnam (Bloodborne): I had an incredibly tough time with this fight, but it was so much fun learning how to do it!
-Rom the Vacuous Spider (Bloodborne): I'm so terrified of spiders in real life, but I love playing games with them so....figure that out.
-Deacons of the Deep (Dark Souls III): A pretty easy boss fight, but I loved it!
-Donkey Kong boss fight in New Donk City (Super Mario Odyssey): Definitely easy, and it barely qualifies as a boss fight, but it was just really fun, and cool!
-Nightmare King (Hollow Knight).
-Red Wine Drunk Randy (South Park: the Fractured But Whole)

Admittedly this is a little lamer than other boss fights people have brought up but I really enjoyed Dark Beast Ganon in BotW

Oh. The Edge from Furi. Most of Furi's fights are great but the Edge was so different to the rest, made you play completely differently.

I disagree, I fought all of those and the fights were very forgettable only now that you mention them do they come to my mind. The character fights all felt very samey and relied more on spacing and taking advantage of openings than actually going in there and dodging attacks like in bloodborne. I get people have different tastes but saying Nioh has the best bosses of all time is a huge jump and your obvious bias is showing. 

Laser slime was a silly fight the boss basically had 3 attacks, the skeleton was just a gimmick fight were you dont really fight but instead go around destroying certain parts. Cant even remember anything about the hydra other than it being visually impressive. As for the oda yuki fight, i found it more annoying/frustrating than anything else. Tons of bullshit one hit kills and instant stagger to death shit, I was probably under-leveled though.

Potentially recency bias here, but if I had to choose at the moment I'd probably say the final boss of DMC5. Haven't been a ton of strong boss fights this gen imo.

Having now played Hellblade, I had to make an addition here.

Valravyn and Fenrir were two of the best bosses I've encountered in years. Both hit that perfect balance between being challenging but not frustrating, and both were fantastic designs whose awesome look was masterfully reflected in their combat style.

Genchiro, because so far he has been the best boss fight in Sekiro. The swordplay in that game is a cut above the rest. Dodging, Deflecting, Blocking, Counterattacking, and being forced to keep the pressure on the enemy in order to win. Other games feel pedestrian with their combat by comparison.