The three games at E3 that may have convinced me to go next/current gen sooner than later are Batman Arkham Knight, GTA V and Assassin's Creed Unity:
Batman Arkham Knight Gameplay Reveal - E3 2014 (http://www.youtube.com/watch?v=YhWQcFTCmpQ#ws)
GTA 5 - PS4/Xbox One/PC Trailer (http://www.youtube.com/watch?v=mzHTUpe_b0Q#ws)
Assassin's Creed Unity E3 2014 World Premiere Cinematic Trailer [US] (http://www.youtube.com/watch?v=-ohFulrJKhI#ws)
This is what next-gen games should look like.