The Victorious skin should be chosen through a poll, voted on by the player base.
I believe Riot should implement a type of poll in which players choose their top 3 champions that they would like to see with a Victorious skin for the season, and would be chosen towards the middle of the season to give enough time to work on the skin - or, alternatively, chosen at the end of the season and we'd have to wait until the middle of the following season to receive the work of art (Victorious Skin). This poll would be hidden to us as the players until the reveal at the end of the season. The choice would be whatever champion had the most votes. Every time a champion receives a Victorious skin, they are removed from the list so they do not get duplicates.
A lot of people say something like: "Oh, get ready for Victorious Teemo/Urgot/Yorick", but I feel like the people that legitimately want a Victorious skin outnumbers those who are trolling.
It's true, you can't please everyone, and no matter who gets it, someone will be upset. However, going based off of a champion that had an impact in one split is ridiculous, and I see that countless people agree with this. I understand it takes time to make a skin, and they would like it out by the end of the season, but there could always be a change, and since we'll be getting the skin in the end regardless, I feel a longer wait would be completely okay. Additionally, you'd have the numbers of the people who chose certain champions, and you'd be able to see that you're upsetting a hell of a lot less people than choosing a champion that has been reduced to rubble over the conclusion of the season.
(in no order)