For me, there are surely 4 things i’ll miss in FGO.
1- Solomon’s Singularity battles.
2- Artoria lancer’s Grand Battle with her astounding theme in the end of Camelot
3- Hessian Lobo boss battles in Shinjuku and his story in general. (loved that he was so good to be able to even kill Jeanne Alter)
4- Onigashima --> the raid battles against Raikou, with the beautiful music theme (whose link i posted, if some people forgot the music played in that raid)