20 kyogre seen, these were the best

Why not both? The Regis will give you three months of rare candies with nothing worth using them on, unless groudon/rayq get rotated in during (likely once sales plummet).

The 15 attack will serve you better, the shiny is just a trophy. However the difference is rather small, if you like the shiny look better / want to brag to friends, go for it.

I somewhat agree with the argument for both but that is kind of dodging the question. Personally I would go with the shiny first - novelty beats almost insignificantly better performance in my mind.

Assuming you have the rare candy why not bring both to level 30 at least? The 91% at most needs one less power up for breakpoints and the shiny is fun to brag with.

Congrats! I would gone for the shiny if I had to choose, it is almost as good as the other. I was very happy with my shiny which is not as good as yours (13/11/12). I plan to bring up mine to 30 or maybe higher