I haven't really played any romhacks besides one. A while ago I played through the Gold Quest for Ocarina of Time. It's like an upgraded version of Master Quest: remixed dungeons, enemies added in different locations, items have been moved to different locations, and some changes to the world outside of dungeons. Great for anyone that wants a more challenging version of OOT.
I've also been watching a friend play through a Pikmin romhack called Bikmin 269. This game is straddling the line between a shitpost and a fever dream. You collect NFTs and Bitcoins, the ground texture is layered images of Shaggy from Scooby Doo, the space ship is a T-posing Luigi, and one type of Pikmin is a "mushroom" that looks suspiciously penis-like... It's a nightmare in the best possible way