I haven't visited any of them, but I looked at their home pages, and checked the Swedish descriptions. Looks like all of them are located in the nature, and neither of them looks like a classic zoo.
They are of course made for tourists, but tourism isn't that big around there, and not around this time so they will probably not be crowded.
Btw. Kungsbyn has a facebook page with some photos. Looks like it resembles a farm with many different types of animals. The other two parks that you mentioned looks smaller.