Premieres December 31, 2024. The new PV is here. Check out the ANN article for additional information. Synopsis from AniList:
In a Holy Grail War, Mages (Masters) and their Heroic Spirits (Servants) fight for the control of the Holy Grail—an omnipotent wish-granting device said to fulfill any desire. Years have passed since the end of the Fifth Holy Grail War in Japan. Now, signs portend the emergence of a new Holy Grail in the western American city of Snowfield. Sure enough, Masters and Servants begin to gather…
A missing Servant class…
Impossible Servant summonings…
A nation shrouded in secrecy…
And a city created as a battleground.
In the face of such irregularities, the Holy Grail War is twisted and driven into the depth of madness. Let the curtain rise on a masquerade of humans and heroes, made to dance upon the stage of a false Holy Grail. This is a Holy Grail War covered in lies.
I’d watch whichever came out first, then call it a day. The format/purpose of them all is the same as far as I know. Battle Royale.