I have both a Congo Grey and a RB2, both males, both raised properly from great breeders, brought up properly, housed, fed, and cared for properly, and I've had them since they were weaned, almost 12 and 13 years ago this year. For all this time, their cages have been in the same area. While they're not "friends" per se, they consider themselves "neighbors" and, I believe, they derive comfort from being near each other. They eat, preen, nap, play, and talk at the same time.
The RB2 grew up with kids just a bit older than your own are now, and I think it made him the social butterfly he is today. He will go to ANYONE and is a complete little showoff. He at one point had a favorite, my daughter when she was a teenager, but now he just likes anyone that pays attention to him. He's been a complete delight to this family. Now he's entertaining a new generation of the family (grandma is grooming the grandkids to love and care for the birds that will be theirs someday). I don't know if all Galahs are like this, because he's the only one I've been around but he's an absolute gem of a parrot. Yes, he squeals sometimes but it's usually short lived. He chews a wood toy the size of himself into a pile of splinters every day. But he's just so wonderful. He is one that talks really, really well. And he has a wicked funny sense of humor and fantastic timing. I love sharing him with others. He goes to rehab hospitals to do his little "show" and he has been to a couple of church and school talent shows and show and tells. So, based on my Galah experience, I vote Galah.

Good luck on your choice.