I'm guessing Overwatch will win the fan vote. It seems to be the consensus multiplayer game of the year, while there are several games that will split votes from fans of single-player.
I voted for The Witness.
I voted for The Witness as well.
I was going to vote for Forza Horizon 3 as that is the game I enjoyed the most this year, but it is never going to win and I loved The Witness as well (although that one probably is not going to win either).
I have started FF XV, but am not far enough into it (and with the story stuff they are going to change I stopped playing it). I do love what I have played so far.
I haven't bought The Last Guardian yet although I bought my PS3 for this game, but I don't really care about it anymore after all these years. I will probably buy it when it's 50% off or something.
Overwatch is not my type of game and although I do want to try it one day, I can not get myself to splurge on it as I don't like FPS games and I don't like multiplayer games (with some exceptions).
I didn't play Uncharted 4 either. I have only played the first one a little bit and I didn't like the gunplay and stopped playing it after some hours (although this is an other game I bought my PS3 for). I did buy Uncharted 4 in a sale, so I will probably try it out at some point. I still think the Tomb Raider reboot and sequel are better games than Uncharted are (I did see let's plays of Uncharted 1-3 afterwards, so I have an idea of what the games are). I haven't seen Uncharted 4 yet. I guess because I enjoy the climbing stuff much more than the shooting and there is more climbing/open world in Tomb Raider (uncharted feels like a linear rollercoaster to me, it all feels fake, which is what I didn't like in The Last Of Us either, although I do like that game a lot more).
(edit: I haven't finished Deus Ex: Mankind Divided either (I forgot about that one). I stopped playing it because Forza Horizon 3 came out and I love the Forza games. I haven't got back to it since. I do love what I have played so far (to me this isn't an FPS game as I do it completely stealth)).
So I guess I didn't play most of the big games this year (they are just not my type of games). I think Overwatch is going to win it as well. Although people seem to be hyped about The Last Guardian at this moment, it is a PS4 exclusive and Overwatch has a much bigger audience. Although it is not my type of game, I do think Overwatch deserves to win it (and I can understand it if any of the games I mentioned win the GOTY awards).