Excellent points Jimmy, I'll weigh in with my 2 cents as well:
Once people can manage to get past the outdated rigid animations, they'll see with extended play that PES is a far deeper, richly rewarding football game than FIFA; the latter's gloss and animations hide a deeply flawed game that doesn't play anything like real football.
I already think PES 2010 was the best version, if they just stuck a new animation system to that I'd be more than happy
FIFA is full of holes and does not represent real football. Don't let the flashy graphics and animations fool you.
4 core specific reasons why it does not match up to PES:
AI and tactics - FIFA's AI is very poor, the movement of the players in general and the defense. There is no midfield. Pressin and physical jostling are overdone. Most games descend into through ball, 1 on 1 and score, whereas in PES I can score a million different types of goals, the satisfaction of scoring is unrivaled. PES' players position themselves better, make better runs and behave like football players should behave. Of course both games can be exploited but PES is better. I can set up my team to play anyway I want with all the tactical options in the menus, the sliders actually make a difference, the man marking and player index's all work and have an effect on the mentality and types of runs players make. FIFA has limited effect because the AI is so poor.
Player individuality and stat based gameplay - This is what PES is known for, I can hardly feel differences in FIFA players whether playing on assisted, semi or manual.
Ball physics - PES has heavy, weighted and realistic ball physics. FIFA feels like you are kicking a balloon.
Ball control, first touch, dribbling system - The combination of ball physics, player stats, the d-pad dribbling system introduced in PES 09 all make the ball control realistic. A lot of people think it's sluggish, its not. It's simulating how players would take touches to set themselves up for shots or to bring the ball under control. Even in 16 directions it is still better than FIFA's hurried style of dribbling, the 360 movement does not compensate for this. PES is more realistic in this sense.
Obviously personal opinion but if you delve deep and ignore the animations, the depth of PES is still there to see. For me 2010 is the best version, even better than the PS2 versions 0_o (I know that sounds like sacrilege). With 2011, I think people will go back to 2010 and see what Konami were trying to achieve, and realize it was a lot better than they gave it credit for.