Played both PES and FIFA on the gamescom. PES was absolutely bad. The AI was makiing very bad decisions. For instance when you had the ball, you winger and back would be in 5 meters of each other. Leaving a big defense gap but also onreachable sides.

As for FIFA. Defensive AI is much better than all the 'analysis' vids on the internet are showing. Only did a head to head game but every player was where you expected him. Graphics are again great.