Are you mostly just trying to pick them based off of the Standard?
I'm not too educated in breeding to the standard, but I have been putting a lot of effort in to learn about breeding to the standard and trying to improve my knowledge. I hope that I can help a little!
The only thing that I can see that stands out to me is that #green seems to have a smaller comb than the breed should carry. Other than that, they all have the correct eye, feather, and foot color.
None of them should carry any positive white on their surface plumage.
I think that #yellow is the best looking out of the bunch. He is absolutely gorgeous. He has good form, looks like he's a decent size, and holds his tail at a really good angle.
#Blue has some nice plumage. It seems that #black and #white are younger, as they are both still growing in some of their feathers.
#Black looks like he is the biggest, no? I like to keep bigger birds, since I have found that now a days most birds are smaller than they should be (or at least used to be when they wrote the standard or when they first created the specific breed).