[Major Spoilers, of course...]
EASILY the ending scene of FNaF 6. 3 and 6 are 100% my favorites story wise because like, in both games you face off against animatronics that relate to the character you play as. 3 is legit father vs. son, while 6 is son vs. father and sister, as well as of course father's victims and the one trying to get the father. It's just a really cool concept in my head. It's made even cooler by the designs. Springtrap is one of my favorite villains EVER. So FNaF 6 putting so many cool things together with great story and comedy and gameplay and serious moments... with that ending being the cherry on top... it's so great. So the FNaF 6 ending is just amazing, especially with the music and the monologue.
Now if only Mangle or Funtime Foxy were in- actually, technically Funtime Foxy was there I guess.