One of my favorite games ever also has one of the best endings ever

Final Fantasy VII

It's another Final Fantasy, this time the entry that's by far the most popular in the series. Final Fantasy VII's ending is as crazy as the story, seeing everything Cloud and Co. go through being pretty much pointless, as the planet ups and rescues itself in the end anyway. Meteor is stopped by the power of the Lifestream, and everyone lives happily ever after. And we see Aerith one last time.
The major part of the ending that gets its place here, though, aside from Aerith's appearance, is the epic fight between Cloud and Sephiroth. The actual final battle is great, and difficult, but once defeated in this form, you get to take on Sephiroth one-on-one in a higher resolution battle that culminates in Cloud hitting his Omnislash special to finish off his effeminate foe. Great stuff.
https://www.youtube.com/watch?v=W4_sw0trdNc