From my experience I would say a nanday is like a huge green cheek conure, but noisy. They are "nippier" (beaky like a GCC) and more active than a sun or jenday and are bossy little guys... but still manage to have the sweetest lovliest personalities. I was very taken by them and birdy sat one once... but the noise they produce turned me away from them. I would say they are about as noisy a sun but louder in volume. They are stunning looking birds as well!
Blue crowns arent really available to us in Aus so I have zero experience with them. It would have been high on my list to own if they were available.
I do own a galah though. They are similar to a conure in personality in some ways (cuddly, playful, funny, great sense of humour, love being touched, learn tricks easily, roll over on their back to wrestle), but like has been mentioned they require things to chew
all the time (in the wild they chew the bark off trees, chew the opening to their nesting sites, chew sticks for fun lol). Almost all require ground time or a foraging floor/box big enough for them to play in as well (in the wild they spend most of their time in fields picking through grass for food). Ours has free roam of the bird proofed loungeroom while we are at home. She makes a huge mess and I sweep three times a day and steam clean every afternoon LOL They also need very regular misting to keep the powder at bay, I mist Mana every 2-3 days and wipe her cage down with a baby wipe daily. They aren't any more energetic than a conure, but if they don't get enough exercise they will suffer from pent up energy and frustration which isn't good for your furniture, your hearing or your delicate skin LOL
She spends most of her time running around being a nutter
They are very entertaining, very intelligent and are like having a tiny feathered human toddler. They are very emotional as well (not as much as a big too, but WAY more than a conure) and for example, if we put Mana in her cage during the way when she is normally out, she will have a toddleresque tantrum LOL They do care about how you feel as well though and generally when I tell Mana off for being naughty she will sit next to me making apology coos and trying to snuggle LOL They are precious with their own posessions as well and if they love something, they will keep it in pristine condition. Mana has a dog bed she LOVES to flip out on which is made of a very delicate suede material and its still perfect, not a hole anywhere. She also has a favourite stuffed lady beetle she carries everywhere like a security blanket, its only made out of felt and by all rights should be nothing but confetti by now... but nope, still perfect. We still have untouched furniture by the way, but only because we keep her so busy every minute of every waking hour that she has no need to chew them.
Sorry for the rambling
We love our galahs
