I wanted the X version so much, but, well, it's kinda complicated and I have to get Y... But I know I will enjoy it anyway, it's not that different from X. ;P
Depends on which pokemon you want. X if you want a blue mega chaizaid(now dragon,chuncher(blue lobster) and you like the fairy type. Y if you want a normal mega charzard,skrelp(a purple toxic sea dragon and you like dark. I chose X because I like blue I like the legendary pokemon. Personly I don't like chuncher or it's evolution so I used the GTS to get a skrelp.