I have never had an event Pokémon (Other than Phione) on my own game. I have had several Event Mons such as Diancie gifted or traded to me by people on here however.
Regardless of form Meloetta remains part Normal Type making it a rare combination (The only others that match it's typing are Girafarig and Mega Lopunny I think).
Both Meloetta forms have very cute designs but I think it is the more 'natural' shade of her Fighting form's hair that gives it the edge for me.
Meloetta is one of the few Pokemon I have never owned. I played Fifth Gen too late to receive the event Pokémon. The developers sure love event Pokémon, unfortunately they are not that common particularly where I am.
I think I prefer the alternate brown hair form to her regular form however.