An easy pick for me but it captures the last decade so well. Lincoln looking at the noose/halo is what sends this one over from being just a funny picture into being genuine art. It should be in a gallery. It should be in the entryway to the White House.
It depends on where you hang out. Gamergate was 2014 and gamers malding over Anita Sarkeesian, which was a dress rehearsal for Gamergate, happened in 2013. I think pre-2013 is too different from the rest of the 2010s, but the rest of the 2010s fit together. Pre-2013 was during Obama's first term when people were still euphoric that change and all that Obama campaign bullshit would happen. Hipsters, scene kids, and lol random humor xDDD were still in vogue, which mostly faded away by 2013. 2013 was also when the gap between meatspace and cyberspace no longer existed. Some Filthy Frank video somehow led to a worldwide meme adopted even by normal people who weren't terminally online. This would've never happened pre-2013, and it's not a stretch to trace that with the alt-right "meming" Trump into the White House 4 years later.