Survey: What do you look for in a ROM Hack?

I'm planning to revamp the lists on this site. For that purpose, I'm interested in knowing what features or aspects of a ROM hack you look for when deciding what to play next. For example, I see a lot of people are only interested in hacks which have the Physical/Special split. And similarly, I know that Fakemons are a turn off for many. I'm mainly looking for important reasons and not just "good to have" things like, say, running indoors, that would not influence your decision much. A couple of examples so we're on the same page: - has a new region - uses the CFRU engine.

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Thanks in advance for any responses!