I like the Pionus species...there are two blue head babies in the store I work at, and the one thing I'd like to say is the reputation that Pionus are quiet apartment birds must be taken on a case by case basis...these babies and especially some adult blue heads I know can really make NOISE!!!
The woman who does most of the handfeeding there feels the Blue Heads are actually the loudest of all the Pionus species she's interacted with. But boy are they beautiful, and they smell wonderful and sweet, and they can be little conversational cuddle birds! They are related to Amazon Parrots, but are more mellow over all and smaller. There are about 5 species you see in the US...the Blue Headed, the White Capped, the Dusky, the Bronze Winged and the Maximillian. They all have a little patch of red feathers at their vent, and their colors tend to really show in bright light...the light kind of needs to hit them right, otherwise they look kind of muted due to the way the pigmentation/refraction works....Bronze Wingeds and Maxis especially! And all are very cute South American birds!!!