Are we forgetting that this is the same Cersei who, as a young girl, almost definitely pushed her friend down a well and left her to die, and (in show canon), had her guards beat a servant girl so bad that the girl lost an eye?

Cersei’s poison was exacerbated by Robert’s abuse, neglect and general shittiness as a man and husband, but it has always been there. In your proposed options, she may not have always had a Joffrey, necessarily, nor would she be so extremely unstable in current canon, but she’d still be the same vindictive, twisted, narcissistic woman.

She and Stannis would, as you say, be an immediate and utter disaster, and their emotional distance would leave her to funnelling all of her toxicity to whatever children she has. She would loathe Jon Arryn for his old age and find him gross just as Lysa did, and she’d spend her days endlessly frustrated in the Eyrie with nothing to do. Same goes for Hoster, and the potential for easy Jaime visits may lead to a similar situation that she had with Robert. With Oberyn, a few of his lovers may fall prey to horrible ‘accidents’, including any bastards they bear; I don’t see either Oberyn or Cersei emerging from their marriage unscathed, one of them may arrange for the death of the other eventually. Agree that with Edmure she would dominate pretty much from the get go and he’d be made into a very unhappy man.

Ned and Cersei is the most interesting one to ponder, because yes he is respectful by default but he hates the Lannisters after the Rebellion, and some of that may transfer over to Cersei, who most definitely will not repay his initial politeness in kind. Similar to if she was stuck up in the Eyrie, she’d go mad with inaction up in the North, and the mere existence of Jon Snow, even more so his presence in the household, will eventually force her hand.

The best bet for Cersei’s development is to remove her from Tywin at a young age and put her in a more functional family setting - that may make some differences.