I both agree and disagree on the Gen 5 being the best thing point.
As far as story and general content goes, I fully agree, Gen V is my favorite. Gen VI is sorely lacking in those areas to me. However, Gen VI brought with it a number of improvements to breeding, the best interface yet(though ORAS's touchscreen has too much imo, doesn't help that the X&Y stuff is its own menu to select in ORAS...), the PSS and in general improved online features, and so on.
So, the actual experience of playing the game is largely improved imo, if only it had content on par with Gen V to back it up. Hopefully S&M will deliver on that point, but with how ORAS turned out in comparison to HGSS and B2W2, I'm keeping my expectations low.