The amount of “yellowness” in 18k yellow is a personal preference but can also, at times, be cultural/regional. Personally I really like a strong yellow.
But my understanding, at least from the recent past, is that the European market preferred a greener yellow. Broadly speaking the higher the copper ratio is the stronger the yellow until, as you noted, pinker tones start to come forward.
But working properties vary across this 18k yellow spectrum.
Generally speaking, and in my experience, the greener (higher silver) alloys are easier to work. But that’s only half the story because the making is the first part of the equation. The life of the “made” when the piece goes out in the world is important to me and I’d rather work with a stiffer, tougher gold that will hold up better.
A little more work on the front end for the payoff on the back end.
As I said, my preference is for a strong yellow. I’ve found that the Hoover & Strong Standard 18k yellow is a really nice yellow and a tough alloy as well. A nice combination for me.
When I moved years ago from casting gold to forging and fabricating it I started by rolling out, drawing or forging the sprues from the castings. As I became more comfortable with it I just started pouring ingots from the left over buttons and then just pouring from the casting shot. I still work this way in 18yellow, 14K yellow, rose, nickel and palladium whites.
Works for me.