X boxart > Y boxart
Xerneas < Yveltal
Mewtwo X = Mewtwo Y
Clauncher > Skrelp
Swirlix > Spritzee
Charizard X = Charizard Y
X boxart looks classy, but neither legendary pokemon is of my liking. Yveltal looks the part, Xerneas looks like the Celebi type of legendary. Possibly it has better stats than Yveltal...on the other hand maybe it is like HG and I will be able to catch a more powerful version of Yveltal in X.
Charizard Y is going to look hella cool evolving from a Shiny version in areas where X already looks great but the Shiny version will look like a straight forward update, Dragon / Fire and all.
X because it has a Pistol Shrimp, honestly that is pretty cool.