I guess I could add Need For Speed reboot to the list if it's going to be like a NFS Underground 3. Also, does GTA V (PC) really count as a 2015 game? The game was released in 2013 and then ported to newer consoles in 2014 and PC in 2015.
The Witcher 3
Batman: Arkham Knight
Star Wars Battlefront
Need For Speed (2015)
GTA V???
Also, it's really a bit over-exaggerating to nail down The Witcher 3 or Batman Arkham Knight as GOTY. EA could pull off a holiday trick by releasing the GOTY late in the year with Star Wars Battlefront. This has happened before in the case of Dragon Age: Inquisition last year.