Gen 6, X & Y specifically, is my least favorite as well.
They try to have a deeper story like with Gens 4 and 5, but they don't really pan out the motivations very well, and most of the characters don't feel like characters.
I mean, really think about it, what can you say about Lysandre? Or the champion, even?
Lysandre's some vaguely insane philanthropist, the champion wasn't even a f*cking character, and they upped the number of rivals to 5 and then proceeded to focus on none of them.