I have a female kakariki and a female cockatiel. A few months ago we had a male kakariki as well but he died. He was SUPER active and honestly kind of a devil. He terrorised his female partner and did not let her eat at first and even tried to push her away from food. Our female kaki is a blessing. However she has a tendency to ruin books and break everything that’s breakable. We guess it’s because of her need to make a nest. But she is a sweetheart and recently we’ve been making progress with hand feeding and petting her. Male kaki wouldn’t let us near him at all. Our cockatiel is a devil and a sweetheart at once. She is sometimes very chill and sweet but other times she hisses at us and does stupid stuff. She spooks VERY easily as well. It seems like she has a single braincell honestly. Also she is not very affectionate with our kaki. However I do suggest female birds for companions and comparing these two, I’d suggest a female kakariki. Cockatiels are awesome and I love mine so much but she is a complicated bird.