Quoted By:
I don't actually remember my first shiny but I think, or feel I think, it was either a Bellsprout or Geodude. Something inconsequential.
My best shiny experience, though, came from XY, when I encountered a Shiny Murkrow in a hoard. I remember this vividly, because I was searching for a regular Murkrow because it is, and has always been, my favourite Pokemon. So whilst it's not really my first shiny, and hoard battles did give greater odds, it is my fondest. I still have that shiny Murkrow, too (prefer Murk over Honchkrow, not to say I don't like Honchkrow); just stuck in Home.