Which type of ROM hack do you like the most
or other QoL (quality of life) where they add things to the base game
i like new region because it's like a base series game
usually 386 is too similar to the main game to me, but if it was done right, could be fun
New region - there's lots of good new region hacks, mostly the ones everybody knows like Gaia, Light Platinum, and Glazed
Open world - there's really only Crystal Clear which is kinda overrated tbh
386 usually isn't implemented properly, I agree. Ultraviolet was too similar to vanilla
Other QoL - Nameless FireRed, Kanto Black, and the countless other ROM hacks like YARFH and Meta FireRed make this category very enjoyable when done right
Considering the current offer I like QoL improv romhacks the most. They get you the chance to play the original game one more time but at the same time enjoying a more modernized experience. So long as they don't trivialize the gameplay too much they tend to be super fine. The one exception is changes to the type chart, or changing the types of Pokémon (instead of eg.: adding variants). Electric/Dark Luxray is a bad meme.
Now, if there was to be a romhack that was done well, ideally using a more modernized base than the usual FR/Ruby, such as Platinum/HGSS, that would be a great opportunity for new region romhacks to shine and I think some cool stuff could come out from that that I would like. But on the current base sets, "new region" romhacks tend to either not feel new enough, or play and feel less like Pokémon and more another-franchise-but-with-mons-tacked-in (eg.: Uranium).
IMO 386-like romhacks fall into the category of QoL improvements even if they have a more special and well-defined place. But merely adding more recent Pokémon (and abilities/moves) does not really add much if any replay value to the current ROM bases unless several other improvements are added in, I feel.
I like new region and other QoL like Dark violet, where the story and region is similar at its base, but changed enough to feel like its a diffrent story. I like those games since i like to have the surprise factor of not knowing where teh difficult battles will occur.