Super Mario & The Rainbow Stars seems to be shaping up that way. Psycho Waluigi gets a lot of praise there too.
I guess stuff like Paper Mario: The Origami King Refolded and Super Mario Eclipse would just be better than their original games too...
My favourite ones that I can think of right off the bat, are
WL4 Parallel World
Ribbit the Deltarune mod
Earthbound Halloween Hack
And a lot of the Pizza Tower fan levels made with the cyop mod are really good too. A couple of them genuinely...
The phrase "[COMPANY NAME] hire this man!" is a meme at this point and I'm sure a lot of us are tired of how overhyped some fan projects can be just to put down the official media. That being said, some fan project are definitely worth the hype...