I played about 15 VNs this year and finished 9, which is actually quite a lot for me. At the same time, none of the VNs I finished this year are that long. Overall, this year I regained some of my original interest for VNs, which I was slowly losing ever since I finished MLA in 2015.
Though they probably deserve to be somewhere in this list, I'm omitting Dies Irae and Seabed since I didn't get that far into these VNs, and there's a good chance that my impression will change later on.
1. Fata Morgana - Requiem for Innocence. Even being a fandisk, this one clearly became my number one, without any real competition. It's not only a nice addition to the original story, but also a very good story in itself that will work perfectly well on its own.
2. Aselia the Eternal. I'm reading this right now, and I've only finished one route so far, but this game is pretty linear, so I think the other parts of the game will be the same. Well, I didn't really expect much from the game when I just started it, but overall this was a nice surprise. Well, I know that this game isn't perfect. There are a lot of very noticeable plot holes, and they definitely could structure the story a lot better. At the same time, the combination of interesting characters, nice ideas, and engaging gameplay makes the experience worth it.
2.5. I guess, Seabed should be here.
3. Chuusotsu. A cute short story that tries to touch some really important themes about an individual's place in society.
4. The Labirinth of Grisaia. The after stories are mostly forgettable, but Yuuji's backstory makes a pretty nice read.
5. Cinderella Phenomenon. Not the best story I've ever read, but still pretty nice.
As for the biggest disappointments this year, this title will go to Phenomeno and Grisaia no Rakuen.