Ravensgryf actually helped me out on that same issue through a different question (I'm planning on getting a White Capped in the future).
Hopefully, I'm not speaking for her but I hope that a few of her tips can also help you. Of course, this is only some advice I found relevant to what you're going through.
"With Pionus, they may or may not be territorial. I can tell you with certainty though, a Poi WILL be territorial and as a general rule the Poicephalus genus does not make friends with other birds. It's just in their nature as a species. In the wild, Poi's do not live in large social groups like conures for example."
Pionus parrots are also prone to respiratory diseases so it's crucial to keep their environment clean.
"If you keep the parrot area clean and it's not moldy around there, I wouldn't worry about respiratory problems. I know Hawaii is humid, but I don't see why you wouldn't be able to keep a Pionus healthy if you paid attention to prevent excess humidity and mold.
Just know that Pionus are a lot like Amazons, in that the males are a lot more temperamental and may be harder to handle upon maturity, and females are more gentle and may even be more inclined to tolerate more petting. Generally speaking though Pionus are not a 'touchy feely' species. Overall, I think female Pi's make "nicer" more laid back pets."
And finally " I don't like Poi's on my shoulder. They're too nippy and their sharp pointed beaks hurt!" (That's one of my favorite, and after I read that I had to look back to pictures of the species beaks).
I have 2 sennies and they hate each other and all other birds. One is fine on the shoulder and the other likes to pinch when she gets stalked and if another animal or human gets too close to me she doesn't just pinch, she chomps.
On the plus side I can do anything I want to either one and I often carry them around like a football couched in my hand. It also doesn't get much cuter when they say, "Peek A Bird!" Or "Wheeeeee!"
I don't want to make it sound like you shouldn't get a bird right now, but try take your time with this. Try visit a whole bunch of different shops or breeders to see which species of parrots you have a closer connection to. Since you have Pi's and Poi's in mind, keep those on the top of your head when you go.
Generally, they live 30-40 years so it is important to have yourself fully prepared. Kudos for your steps on learning different species prior so you know what you're getting into!
Try seeing if there are bird fairs anywhere near you. It's also a good place to get information. They have birds there on show so you can see all different types in person. You can even buy supplies there sometimes on sale so if you wanna set up your future birds cage first you can shop around there! Good luck finding the right bird! African Greys are my favorite but they are way to high maintenance for me at this stage in my life.
I just now saw this thread!! Yes, I have both Pionus and Poi relatives (close enough to a Sennie lol).
They're both different, but one thing they have in common is they're VERY independent birds (unless they were raised to be more clingy, but it's not in their nature). I have to say as far as parrots go, mine are pretty easy. They're not a bit demanding if I'm extra busy, and have no problem self entertaining.
First, the Poicephalus parrots which include Senegals (if they're handfed and handled regularly from a very young age) can be very hands on and cuddly. They're really the only genus that I can think of that can be both that cuddly and that independent at the same time. IMO, the only drawback to Poi's is that they can be extremely hard biters for their size. They do tend to freak a little more easily than some birds, and tend to bite first and ask questions later. Many individuals of this genus are on the nippy side, and training can only curb it so much. It's just in their nature. Doesn't deter me though. I'd get another Poi if I could. As far as parrots go, quiet too! Although quiet is relative, any parrot can be noisy or loud to some people. Don't expect any parrot to be as quiet as a cat!
Pionus tend to be more reserved and cautious. Especially at first. They look before leaping, and study their surroundings.. and as you study them, they're studying YOU! Much in the way Eclectus do, or what I've heard of Greys? Many Pionus are hands off even when hand raised. About like an Amazon, Grey, or Eclectus in that regard. Like their close Amazon cousins, they usually show a clear warning before biting. Something that Poicephalus don't always do. Generally... FEMALE Pionus make easier going pets especially after maturity. Males may be more difficult to handle during hormonal seasons, and might be a little more aloof than females. A female might also be a little more willing to be petted than the average male. Hope that helps. Ask more if you have any questions!