I recently came across a colorization that turns the original black and white/green version of Pokémon Red for the GameBoy into a proper GameBoy Color title. This sent me down a bit of a rabbit hole, but the sheer number of hacks that have been made over the course of several decades is slightly overwhelming, so I'd love to get a decent first selection by hearing which are your favorites that have improved or transformed console and handheld games in meaningful or entertaining ways.
Thanks in advance!
One big favourite is the fan translation of Mother 3 for GBA.
I tried to avoid translations in my list. But anything by Aeon Genesis is also great, so is Mother 3 with the Tomato Ring. The SMT translations are a high point too.