Figured I would throw in my two cents.
The biggest problem with a poll like this is it is really hard to give a blanket answer for the characters. You need to judge their human form, CPU form, and personality to try and give an accurate opinion of who is your favorite. So anyone voting for Iris/Yellow Heart is obviously just going by pure appearance. Then if we're going to consider appearance only, which game and which form? Also in the case of Vert and Neptune, which personality since they are so radically different as human and CPU?
Some examples of my point on my own opinion.
HN CPU: Green>White>Purple>Black
HN Human: Black>Purple>Green>White
V CPU: Green>Black>Iris>Purple>White>Yellow
V Human: Black>Iris>Green>Purple>White
Personally I voted for Blanc, because I love her personality and her CPU outfit in HN. However as shown with my previous examples, my ratings could swing a lot if what we were voting on was specified a little more. That being said, I'm not complaining, just commenting.
"Among creatures born into chaos, a majority will imagine an order, a minority will question the order, and the rest will be pronounced insane." ~Robert Brault