It’d be tough to give an exhaustive list of which animals I feel it’s morally wrong to keep as pets and which I don’t, because it really is a species-by-species basis. And there are exceptions on both ends- both animals that have very good lives in captivity thanks to capable owners and owners who I would never want to own a cat or dog, much less an exotic pet.
It’s annoying to hear the conversation on exotic pets get sidetracked again and again by the same meaningless statements: on the one hand you have the people saying “that animal belongs in the wild!” which is nice, but adds nothing, and on the other hand you have “cats and dogs used to be wild too!” which just mind-numbingly tosses thousands of years of evolution to one side.
I mentioned before the three* criteria I use when thinking about whether or not I’m morally comfortable with certain species as pets. They are: is the animal captured and sold directly from the wild or does it breed easily in captivity? can the animal be rehomed? and of course, can the animal live a fulfilling and healthy life in captivity?