Ok... here goes. Lol
Galahs make EXCELLENT pets. Fairly quiet, rather playful, they're considered the quietest of all 'toos, not terribly needy or troublesome (not near as cuddly as other 'toos though)
Major Mitchels (leadbeaters) are a lot like Galahs slightly more noisy, and tend to be a little more difficult to tame. Some people say they make terrible pets, but in reality they're not bad. Although our friends aviary has 3 for sale now and one male throws his crest up and hisses every time he sees me... no idea why, I've never touched him or anything. Her other two run up to me for attention, so I recomend you MEET a major mitchels in person.
Goffins are really fun and cuddly, but incredibly active and loves to find trouble! They almost always have to have all cage doors padlocked shut.... (Statistically the most common Goffin name is Houdini)
Big 'too (U2 and M2) require their owners to be nearly as insane as they are.... I LOVE big 'toos, but they have BIG voices, and our maile umbrella had to have a cage special ordered because. He could pop welds and remove bars on the best of cages

lol!
The sulfer crest family can almost be lumped together, (yes they differ from eachother, but not enough for me to type it all out on my phone). This includes, Greater, medium, and lesser sulfur cresteds, citrons, and galerita galeritas.... they are a playful and independant bunch. The Galerita Galerita is a prissy bird and VERY rare and hard to find. I had never even seen one in person until a few months ago. (Most people here won't even know what it is, and google isn't gonna help...lol. Anyway Citrons being the most playful and fun of the bunch, but they do well aas pets because they play well by themselves for the most part and are easy to keep happy.
Now, I personally recomend one of the following...
Bare eyed cockatoo (less nuts than a Goffin, and just as fun, plus cuddly)
Slender bill cockatoo (clownish and sweet)
The bare eyed and slender bill 'toos are in my opinion the most stable minded, with a wonderful balance of playfullness and cuddling. They are also a quieter 'too like the Galah.
These are just my opinions.... I own 10 'toos and rehab lots of them, so 'toos are my specialty
