I'm snagging quite a few of them for my personal collection. I personally love number 19/20♥ and I think I might use that one (20). I also think that your Yuuko one is quite stunning as well. You do great coloring, it has a different mood for each icon, like the picture itself.
On a random side note, is it just me or do the girls from Negima look like Clow Cards? They're so cute, and the color selection on them remind me of cotton candy. Good Job!