I think I'd have to go with Nate Spergwood overall.
Honorable mention goes to Brexit and especially the US elections, which provided mountains and mountains of salt from almost every single lolcow and even normies.
Some other memorable moments from last year:
Null: Started a pissing war with trannies, one of which drove to his house armed with knives/crossbow as Null hid in the bathroom
Vordrak: Buttblasted about having a thread mocking him, so dedicated to getting it taken down he started emailing terrorist threats to maternity wards and working with other cows such as Laurelai and Nate Spergwood
Brianna Wu: Game finally released on Steam, with a game-breaking bug at the end which he never patched (afaik). He fought the alt-right and won, now he's running for congress
Chris-Chan: He thought he grew a "vagina" by listening to YouTube videos. He also flipped his shit about Donald Trump and started staging mock executions and trashing his toys in anger
Shmorky: I don't know if this counts as this year, but those leaked ERP logs were like a disgusting drama bomb that's had multiple communities riled up and infighting
Peter Coffin/Zoe Quinn/etc.: Similar situation as Shmorky's, one of their 'friends' fucking them over by releasing their private Skype logs may not count towards this year, but man there was some good salt there. Despite the best efforts of 20+ of these idiots working together, 8chan is still here
I know i'm forgetting some good drama from last year but it's hard to remember it all when the Trump Train caused such a massive avalanche of salt and cows have been chimping about it nearly every day since.