Someone mentioned MGS4 already, that was my pick. Everything from the final duel to the very end is fucking perfect.
So I'll go with Persona 3. While I prefer P4 and P5 overall, I love the ending to P3. It was perfect.
The Answer promptly ruins the ending, but I hate The Answer as a whole, so...
The Spectacular Spiderman. My God, that show was excellent. Does more with 26 episodes than most shows with longer runtimes.
They were really hitting their stride, and set up some great things for Season 3. Outside of Spiderverse, Spidey hasn't been that good since it ended.