I don't know if there is a technical term for it, but try to find one that looks clean. They will age better.

For example here is my girl Kali when I got her:


As you can see she's not very clean in color (maybe uniform would be a better term).
This is how she looked in January to give you some idea of how she aged:


She has held some of her yellow very well, but she's no where near as nice as my other bee Stella:


Stella is about half the size of Kali but you can see that she looks much nicer. If I remember correctly she was headed into shed in that picture too. I believe she is going to hold her yellow color very nicely.

I hope that helps some in addition to what everyone else has said.