If I can get through a game without having to look at the stats screen even once and it still feels like a satisfying experience that feels like a good stats system to me 
Don’t get me wrong, I’ll definitely use it to check on character relationships and personality- or alignment stats every once in a while, but if I have to look at it before every choice to try and puzzle out what stats correspond with what the author may or may not have intended with each option that’s a huge disappointment, especially if it doesn’t make sense with the narrative of the story. To use ZE:Safe Haven as an example, you can choose from different military professions. From a story perspective it should mean your character has at least had a military training and, depending on rank, field experience. Yet the skill system completely overrules this. This is most obvious in skill checks to do with firearms and (military) vehicles. You can fail at those to an extent you would never have been able to get into military training, let alone make a career out if it. Ehm… Rant over.
So yeah, from a story>game mechanics perspective good stats are stats that track the MCs relationships with other characters, alignment, attitude, and similar subjective stats, and if it’s a game using skills, skills that aren’t integral to the MCs backstory, open up “extras”, like for example different story branches or flavor text, in the story, do not limit the player to the one path corresponding to that skill or fail automatically, and can be improved through the course of it.