I really liked anything to do with Ezreal. I know that might seem underwhelming to some--even I can admit that while his stories were well-written, they were not the best of the year, nor were they breaking any fantastical new ground. However, I love the characterization of Ezreal, how he's just this delightfully cocky bastard that most people probably want to punch in his pretty face, but can't because he's actually really good at what he does. I think we all knew or some of us were the kid that barely had to try to succeed in high school, and Ezreal is that guy cranked up.
The thing that really makes it work is the set up as to why he became an explorer. His parents were somewhat neglectful, and you can see that even though he's great at everything he does, he has this constant need for approval. When his parents disappear inexplicably, instead of coming to the likely conclusion that they met their demise exploring the Shuriman tomb, he is completely under the disillusion that if he was just good enough his parents would obviously return. Which adds a tragic element to his character; here's this kid who has talent and the resources to back it up, but he's really lonely and is in real need of an actual friend.
Ezreal's new lore makes me look forward to what's coming next. He has huge character development potential, and his stories could include practically any region in Runeterra, which is really exciting.
Another mention of mine is Confessions of a Broken Blade, for actually progressing the stories of two characters and finally officially connecting them. I liked the old couple that defended Riven, both Riven and Yasuo were characterized well and the blade both "confessing" the truth as its role as evidence while also being a metaphor for the "broken" Riven's confessions was nice. It was very enjoyable to read.