In-game? Probably Dunsparce since it's been my "mascot" for so long, but Mothim is REALLY tempting since I worked harder for it than any other Shiny (a nearly year-long hunt!) and moths are kind of my thing IRL.
As a character in the anime, manga, etc.? I'm kind of wanting to say Eevee since it, going by its GSC colors, reminds me more of my Ciel than any other canonically-colored Pokémon (next to non-Shiny Espurr, but it's technically based on a Scottish Fold so it doesn't really work for me). Not clearly a cat, but at least a couple of its evolutions definitely seem feline-inspired (like Espeon) and its creator
did liken it to a
fluffy cat or dog-like creature in
this little back-and-forth, so good enough?
(If non-canon colors are fine, maybe a grey Torracat instead.)