Supposedly the cyan is nicer on the eyes. It's also closer to my original avatar, but it's actually had a blue-green color blindness filter applied to it to make it look nice. The reds and blues produced by are intended to look nice to regular people, which is why I chose this over the green lines.
On the other hand, the color that my avatar is currently just looks like glorified gray to me - red-green color blindness doesn't mesh well with the blue-green. I'm pretty sure if you have both you've just got full on black/white/gray vision.
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Attached are examples of blue-green and red-green color blindness, in that order, and what my current avatar looks like to me.