Grisha wrote:
In actual practice, I am indifferent - beautiful eyes are much more subtle than simply the color of the iris.
If forced to choose, I vote blue because it made me think of Sunshower's eyes - which everyone knows are gorgeous...

Aw... you flatterer!
Personally, I've never really had a preference. I like my own eyes mainly because they are a useful tool in photo art - they are a strict blue; not too dark, not too light, almost like a primary blue and so work well with other colours. As far being attractive though, I always considered them a bit boring in some ways - not super light or super dark, not mixed or unusual. Just straight blue.
Sometimes if the backdrop is right they can look deceptively green in a photo... which awesome... but really doesn't happen much.
Blue:
Green:
Eyes that change colour naturally would be sooo useful. But then I'd have to control the colour change anyway to be able to use it effectively, so that's impossible anyway.
But yeah, aside from my bright colours obsession and art, I've never really even registered eye colour much. As far as attraction goes, for me eyes are not a factor really, except I find overly intense and prolonged eye-contact disconcerting and thus unattractive. But again, that's not specifically related to eye colour.
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Into the dark...