This is when I stopped watching E3 coverage.

2015.  It wasn't just that there was a lack of announcements,  it was just so poorly planned and done.  First they wasted multiple worthy announcements in a mini direct before E3, then they reduced games of substance and quality to small showings - Xenoblade X was, like it or not, their big Holiday title and it got the least attention at E3 2015 of all the E3s it was in - in favor of hilighting the very weak and undercooked Star Fox Zero.  Then just for good measure they delayed revealing Pokken for no reason other than to solidify the conference as a resounding disappointment.  It was one of the most baffling E3s I've seen.  

2011

That was the year that they announced the Wii U.  Nintendo really pissed me off with that.  That is the moment that I realized they had turned their back on everything that they'd created with the Wii including all of their new customers.  All of the other garbage that came from later E3's in the 2010's can be traced back to this one.

2015. Many mistakes were made.

2012 was really rough, too. The Wii U games didn't seem to bring much to the table, and they ended the show with stupid in-game fireworks.

Surprised there's not more votes for 2011 and 2012, those shows were truly dismal and in hindsight really set the tone for what would be a disastrous generation for Nintendo; poor messaging, a lack of games, uninteresting hardware.

2012 I'll give you, but 2011 stirred up a lot of interest and at the time looked promising enough.  It all fell apart a year later as we know now, but neither has anything on 2015 which not only lacked a lot of new stuff but utterly failed to properly market anything they had there.

The other horrible aspect of 2011 though was that it basically confirmed the last 1.5 years of the Wii were going to be a barren desert.

E3 2013 is aging really well, I think. 3D World and Tropical Freeze sucked as announcements, if only because of everyone's Galaxy 3 and Metroid Prime 4 predictions, but now they're two of the best platformers around. And Mega Man certainly brought the hype even at the time. Back in the day, it was the worst, but now it's in the middle of the pack in my book.

Well, I think it's safe to say 2015 is the undisputed "winner" here.
It is nice to see I'm not the only one who hated 2018 though haha

2012
Pikmin 3 was a good announcement but I barely remeber anything outside of the Nintendo Land fireworks.
It was a meh E3 launch that foreshadow the not so good life of the Wii U.