i think a question that people should ask themselves when bringing an animal into their life is: will i take care of this animal for its entire life? people really underestimate the life span of birds, which can range from 10-100 years. rheas have a lifespan of 30-40 years in captivity. if you are ~20-years-old, do you see yourself caring for this bird in your 30s, 40s, 50s and 60s? if not, it would be best to pass.
with that said, one should actually determine if the animal's personality matches the human owner/companion. a rhea is NOT a HOUSE pet. it will be in your backyard, which should be the size of a farm with many acres. one should also see if its ethical/legal to own a particular animal. a kiwi is actually an endangered species. its not even social, even amongst its own kind.
research the animal to make sure it fits your personality and its ownership won't get you arrested.