If Bioshock Infinite had stayed closer to the demo that was shown during E3 2011, I would have probably considered it the best:
The demo just made the environment, enemies, and Booker and Elizabeth seem much more interactive than what was experienced in the final product, which I didn't think broke as much ground as the original. While I still enjoyed Infinite, that demo inflated my expectations of the game. Thus, I still consider the original Bioshock to be the best entry in the series.