Petty question.

Which has the higher number attack iv? ;)

I just took my 100% regular Articuno to level 30, but then I ran out of candy. Power the 98% and trade the shiny. If that offends you, power the shiny instead. Or you can power the one with 15 attack.

But tbh are you really gonna take either to 40? Might take me a whole year to get my new 100% to 40...but I might actually do it since I'm a closet Mystic zealot

There are no petty questions here.....because they're all petty.
I'd personally power the Shiny and take down Rayquaza in style

Umm, what's wrong with both? Just do more raids for rare candy, and make sure your Rayquaza, Kyogre, Groudon, Palkia, Dialga, Moltres and Raikou are maxed out already. Ummm, okay, yeah, never mind.

Do both. 496 rare candies YOLO.

Well, I was in the same situation with my Lugia collection. I chose the shiny 93% over the regular 98% because I am stylish like that.