I never use articuno on my team but it's always been a bro to me since the first gen.
My little kid self used to love ice and water types and so articuno was naturally my favorite legendary after mew.
Articuno would also usually let me catch it in just one pokeball, making me feel as though it "chose" to be with me (remember using anime logic in these games?)
I was also the first child of three and Articuno is the first bird that gives off that vibe of being a leader to its siblings so I continued to like it as I grew up due to self reflection.
Later, the first random shiny I've ever encountered was a horsea in FireRed with a fishing pole in the Seafoam islands.
Jump ahead to this gen and I successfully didn't spoil X for myself. I chose Chespin because the fennec fox looked like a littlest pet shop purse chihuahua and the frog looked like my grandma.
My little brother (second child) finished his Y game before me because he's a no life faggot and he saw Zapdos in the grass. I get excited and get to that point as well to find out that I get Articuno instead.
Takes me longer than this kid to confront my bird in its cave, and when I do it lets me catch it in just one pokeball just like old times

So all in all I just think Articuno's a pretty chill bro. Reminds me of a matured form of my younger self