I don't love any game. I have all ISS/PES titles and FIFA from 98 to 2009 (PC only). Haven't bought FIFA 10 and 12. Bought 11 and 13, got 14 for free from mate.
I just know history of both titles on PC market and how all changed. Maybe that's where the difference is.
PC users up to FIFA 10 were offered absolute crap of the game based on PS2 engine. Back then PES was viable option to play as it offered better gameplay and graphics, even when some titles were badly optimized (PES 2008 and corners caused stuttering). Until PES 2010 it was better game.
But with FIFA 11 the tide that came swept ground clear. KONAMI was pushed back then and should have realized they cannot come with rubbish anymore. They started to lose clients even on PC.
Now let's come back to Pro Evolution here. PES 2008 was actually quite playable, still using PS2 core, but with updated graphics and with added, what I thought back then, best AI yet in football game. I mean Teamvision AI and how AI learned how you play and delivered strategies to beat you.
No magic boosting, but play the same way vs AI and you will in the end be punished. That was something yet unseen in football games.
Back then, remember skills/tricks were still performed on right analogue stick.
PES 2009 changed control scheme (for what reason, I don't know). Now feints, tricks were performed on left stick alone.
Not much to say about AI, but it degraded in my view. The AI started to play in same way, same pattern all the time.
PES 2010 was the best looking PES. Graphically wise the colors were vivid, lively, not flatten out, the level of details was v. good out of the box.
Pretty good on the field too and they added 360 degree movement (well, partially) to it.
Here I take big breath now. It was year 2009 when PES 2010 and FIFA 10 were released, but... Back then EA Sports came with surprise announcement (Ian actually from Beautiful Game Studios). They said: next FIFA will be using NG engine on PC.
What went through Seabass mind back then, I would rather not know. However, PES 2011 came out and... In some ways it was worse than PES 2010.
I don't want to go into details, but it was then when they announced proudly 1000 new animations were added. Sure, it could be felt and seen. When you passed the ball and the guy... Decided to go round the ball to touch it with right foot.
It happened quite frequently ruining something PES was known for. Fluidity.
Add to that inconsistent passing system which was KONAMI/PES answer to ProPassing which mixed randomness with angering people script. What I mean, touch the button lightly and ball goes 20m from you, do the same next time, the ball barely moves away from your foot. Took time getting used to, but for first few games I had WTF is happening there moments.
PES 2011 also introduced the plague we have nowadays. Terrible and I mean terrible goalkeepers. They made some World Class saves of course, but... Whole image of them could be broken in one moment in game when they let ball go to the net straight through their hands. Didn't matter if it was van der Sar or Cassilas in goal.
There is one more problem they haven't addressed till now. There are only 3 states of player movement possible. Stand still, jog, sprint. Mix into it slow turning animation.
No in between states.
PES 2012. Again changed from PES 2011. Sped up the game, sped up animations, AI was dribbling and through balls king. The GK were not addressed which led to funny scorelines

.
PES 2013 - the best version they could have built PES 2014 on. It had almost all fixed already with last patch. They needed to upgrade some stuff, try and make Football Life more emerging, overhaul menus, etc. Fix some gameplay annoyances here and there. Bump up graphics (it could be done if you look at player based turfs

. Why they didn't do that is beyond me.
PES 2014 is half assed backed game. Unfinished. They took out stuff and that's massive crime. The AI, Goalkeepers and other stuff I don't want to repeat. Enough has already been said about that.
If they wanted to give this generation proper goodbye they could have done it. People would have forgiven them if they offered CG PES once more this year, but much more polished.
Then they could prepare for NG PES introduction, but with all stuff in it.
You may love the franchise, sure, but it's clear they lost their way. Unfortunately like I said, I can't see PES going out of the gutter in KONAMI hands.