I really appreciate a good ending, but what isn't mentioned as much is how the end credits can really elevate it if done well. I am not just discussing the credits song, though it is important (there are already two threads dedicated to that), but also the visuals, font, any interactivity, even length!
I can think of a few examples of the top of my head, though I am sure there are more. Undertale had a basic shooting gallery ending where you can find a secret, the Stanley Parable had a credit museum in one of its endings, which you can walk around in to see the development process and both Portal games of course had their in universe ending songs where lyrics appear on a computer screen and Glados sings.
My favourite end credits are in What Remains of Edith Finch. The camera slowly pans down through the floors of the house as pictures of the developers as children litter the wall and shelves. There is something really eerie, yet vulnerable about those credits. It really got me to think back over the whole game and what it might be trying to say.
Those are just some examples which popped up. Please share your own suggestions in the comments! I don't personally mind spoilers, but keep in mind that there is a good chance you might see some due to the nature of the topic.