Generally, almost all species of parrots are considered to make good companion parrots. All larger varieties of parrots, such as Amazons, African Greys, Cockatoos, Eclectus, Hawk-Heads, Keas and Macaws; most mid-sized birds such as Caiques, Conures, Pionus, Poicephalus, Rose-ringed parakeets, and Rosellas, and quite a few of the smaller types including Brotegeris, Budgies, Cockatiels, Grass parakeets, Lovebirds, and some Parrotlets are often considered companion parrots.
Species of pet parrots that are not generally considered companion parrots include Lories and Lorikeets, Hanging parrots, and Fig parrots, fruit and nectar eating birds which are generally kept in colonies. Such species as Pygmy parrots and Kakapos, Night Parrots, and about half of the species of parrotlet, are not considered companion parrots due to the apparent impossibility of keeping them alive in captivity for extended periods of time.
Generally, depending on one's definition of a good pet though, the definition of a companion parrot can vary considerably, and there are some in aviculture who go by the individual parrot rather than the species.